I will just give general principle why Bhagavatam doesn't teach Advaita according to the opinion of Gaudiya Vaishnava school
We need to carefully look at the speaker and writer of Bhagavatam to fully ascertain its teachings.
Sukadeva Goswami was situated in transcendence and enjoyed within himself.
Sukadeva Goswami describes about himself and superiority of bliss in bhakti.
“O King Parikshit, most topmost transcendentalists, who are above the
regulative principles and restrictions, take pleasure in describing
the glories of the Lord. At the end of the Dvapara-yuga I studied this
great supplement of Vedic literature named Shrimad-Bhagavatam, which
is equal to all the Vedas, from my father, Shrila Dvaipayana
Vyasadeva. O saintly King, I was certainly situated perfectly in
transcendence, yet I was still attracted by the delineation of the
pastimes of the Lord, who is described by enlightened verses.
Therefore I studied this narration” [Bhag. 2.1.7-9]
The above message was also briefly defined the description of Badarayana's trance found in 7th chapter of 1st canto.
“Thus he fixed his mind, perfectly engaging it by linking it in
devotional service [bhakti-yoga] without any tinge of materialism, and
thus he saw the Absolute Personality of Godhead along with His
external energy, which was under His full control. Due to this
external energy, the living entity, although transcendental to the
three modes of material nature, thinks of himself as a material
product and thus undergoes the reactions of material miseries. The
material miseries of the living entity, which are superfluous to him,
can be directly mitigated by the linking process of devotional
service. But the mass of people do not know this, and therefore the
learned Vyasadeva composed this Vedic scripture [Shrimad-Bhagavatam],
which is in relation to the Supreme Truth. Simply by one’s giving
aural reception to this Vedic scripture, the feeling for loving
devotional service to Lord Krishna, the Supreme Personality of
Godhead, sprouts up at once to extinguish the fire of lamentation,
illusion, and fearfulness. The great sage Vyasadeva, after composing
the Shrimad-Bhagavatam and revising it, taught it to His son, Shri
Shukadeva Gosvami, who was absorbed in renunciation” [Bhag. 1.7.4–8].
“Shri Shukadeva Gosvami was already on the path of self-realization, and thus he was pleased with his own self. So why did he take the trouble to undergo the study of such a vast literature?” [Bhag. 1.7.9].
Suta Gosvami replies:
“All different varieties of atmaramas [those who take pleasure in
atma, or spirit self], especially those established on the path of
self-realization, though freed from all kinds of material bondage,
desire to render unalloyed devotional service unto the Personality of
Godhead. This means that the Lord possesses transcendental qualities
and therefore can attract everyone, including liberated souls. Shrila
Shukadeva Gosvami, the son of Shrila Vyasadeva, was not only
transcendentally powerful. He was also very dear to the devotees of
the Lord. Thus, his mind captivated by the enchanting qualities of
Lord Hari, he underwent the study of this great narration
[Shrimad-Bhagavatam]” [Bhag. 1.7.10–11].
The phrase bhakti-yogena (“through devotional service,” [in Bhagavatam 1.7.4]) means “through love of God,” since the same meaning is conveyed in the following statement:
“My dear King, the Supreme Personality of Godhead, Mukunda, sometimes
grants liberation to those who are engaged in getting His favor, but
He rarely grants bhakti-yoga, pure love for Him” [Bhag. 5.6.18].
The purusam purnam of SB 1.7.4 refers to Krishna, it becomes clear after few statements in 1.7.7 the words kṛṣṇe parama-pūruṣe is used.
Thus svayam bhagavan Krishna(1.3.28) is referred and by doing so brahman and paramatma are also included(sb 1.2.11) & his internal energies are also included.
The phrase mayam ca tad-apashrayam [in Bhagavatam 1.7.4] to mean that Maya takes shelter of Him in an inferior position, hiding from His sight; thus she does not constitute His svarupa, or essential nature. As it is said later on, “Maya, feeling ashamed, doesn't stand in the Lord’s direct presence” [Bhag. 2.7.47].
That Shri Vyasa saw the distinction between Lord and living entity is shown by the verse beginning yaya [Bhag. 1.7.5]. Although the living entity is by nature pure spirit, transcendental to the three inert material modes, when deluded by Maya he considers himself a product of those modes, the inert material body. This delusion causes the living entity to suffer unwanted consequences, namely the miseries of repeated birth and death.
Thus is refuted the contrary opinion that the jiva exists only as an upadhi of Brahman and that liberation is simply the elimination of this upadhi.
Here [in Bhag. 1.7.5] the phrase yaya sammohito shows that Maya alone is responsible for deluding the living being; the Lord remains uninvolved.
Like the Lord, the jiva is purely spiritual, yet still he is different from the Lord. This truth is indicated by the words tad-apashrayam (“Maya is outside Him yet supported by Him,” [in Bhagavatam. 1.7.4]) and yaya sammohito (“deluded by Maya,” [in Bhagavatam. 1.7.5]).
If the conclusion were ultimately non-difference of the Lord and the
jiva in Bhägavatam, it would be stated that Vyäsa had seen that by
ignorance, the one Brahman would become different
(producing jéva) and that by knowledge, suffering caused by difference
disappeared. Since the Lord’s pastimes would become completely
unreal, this conception is contrary to the heart of Sukadeva
But that is not stated. Vyäsa saw the complete purusa(Krishna) and the jéva bewildred by mäyä which took shelter of the Lord and he saw bhakti of the Lord which destroyed the anarthas.
Scriptural statements concerning jéva as a limitation or reflection of Brahman are employed with guna-vrtti (secondary meaning) to show similarity.
The argument and conclusion are stated in the following:
ambuvad agrahaëät tu na tathätvam
There is no similarity because one does not see distance between the
Lord and the jéva as one sees distance between the sun and water to
cause the reflection. Brahma-sütra 3.2.19
våddhi-hräsa-bhäktvam antarbhäväd ubhaya-sämaïjasyodevam
The comparison with the sun is accepted in the sense that it
illustrates the nature of greatness of the Lord and dependence of the
jéva, since this is included in the scriptural conclusion and
harmonizes the elements of the comparison. Brahma-sütra 3.2.20
The scriptures describing reflection and bifurcation are used to show similarity to reflection and bifurcation using gauna-vritti. Devadatta is a lion. By gauna-vritti it means that Devadatta is similar to a lion not that he is a lion. “How can this be determined as the meaning?” Vyasa has shown this in two sutras.
The first sutra refutes both propositions (bifurcation and reflection) because of their impossibility. A piece of land is cut by water and Brahman is not cut by upadhis. Brahman cannot accept upadhis as land is cut by water. Sruti says agrihyo na hi grihyate: Brahman is not subject to any upadhi. (Brihad-aranyaka Upanisad 3.9.26) Thus it is not true that Brahman is cut by upadhis.
The reflection of the sun is seen in water as a fragment, but the reflection of Brahman is not seen since Brahman is all pervading. Brahman does not have a reflection.
What do the scriptural statements mean? The second sutra answers. The two statements do not employ mukhya-vritti (literal meaning). The examples are used to illustrate only qualities of jiva and Brahman (vriddhi-hrasa-bhaktvam). Thus the Lord and jiva are a big piece of land and a small piece of land or the sun represents the Lord and the reflection indicates the dependent jiva. Why? Because taking the partial analogy fulfills the meaning of scripture (antarbhavat). Only by taking this meaning is there a correct correlation of the object and the compared object.
In the first sutra both proposals are refuted. In the second sutra, the truth is established by gauna-vritti. The opinion of the author of the sutras is that the jiva is like an amsa or reflection of Brahma.
Therefore the scriptural statements instructing us about the nondifference between the jivas and Brahman should be reconciled so as to agree with the conclusions Vyasa came to in His trance. This is accomplished by first removing the apparent contradiction in the jivas’ being both different and nondifferent from Brahman: From these statements teaching nondifference we should understand that the jivas are one with Brahman in the sense that both they and Brahman are pure spiritual entities, while by Brahman’s inconceivable, natural potency, which makes even the impossible possible, the jivas are also innately distinct from Brahman by virtue of their being His parts, like the infinitesimal rays of the sun’s light.
In summary, what follows are the ideas underlying the Vedic statements that speak of the oneness of Brahman and the jivas, employing the analogies of reflection and delimitation:
The jiva, like Brahman, is by nature purely conscious.
The jiva, like Brahman, is distinct from matter.
The jiva is one of Brahman’s energies.
The jiva is eternally dependent on Brahman.
The jiva can never be absolutely one with Brahman.
The jiva is constitutionally the eternal servitor of Brahman.
The analogies of reflection and delimitation help us understand the purely spiritual nature of Brahman.
For the verses that you quoted, either full/partial answers are available already. Refer How non-Advaitins interpret 12.5.11 and the partial explanation of 12.13.12 here
Answer is based on Tattva Sandarbha of Jiva Goswami