It is said in Shrimad-Bhagavatam (12.13.12):
"And that one thing is the only goal of this literature"
The "one thing" referred to here is pure love for the Lord.
The preceding three quarters of this stanza describe the Lord. Therefore this last quarter should also be understood to refer to Him.
In the preceding stanza it is said (Shrimad-Bhagavatam 12.13.11):
"Shrimad-Bhagavatam is filled with nectarean descriptions of Lord Krishna's transcendental pastimes, descriptions that delight the
These words affirm that pure love for the Lord is the primary topic of Shrimad-Bhagavatam. The words "hari-lila-kathamrita" mean "The descriptions of Lord Krishna's pastimes are nectar", and the words "sat-suram" mean "The self satisfied (atmarama) devotees.
The glory of pure love for the Supreme Personality of Godhead is also described in these words of Shrimad-Bhagavatam (10.12.11):
ittham satam brahma-sukhanubhutya
"Lord Krishna, who awards the impersonal brahman realization by His
bodily effulgence, also gives pleasure to the devotees as the Supreme
Personality of Godhead. Those who are under the spell of external
energy, maya, take Him only as a beautiful child. Yet He gave full
transcendental pleasure to the cowherd boys who played with Him. Only
after accumulating heaps of pious activities, those boys were promoted
to personally associate with the Supreme Personality of Godhead."
It is also described in these words of Shrimad-Bhagavatam (2.1.9):
parinishthito 'pi nairgunye
"O saintly king, I was certainly situated perfectly in trascendence,
yet I was still attracted by the delineation of the pastimes of the
Lord, who is described by enlightened verses."
Therefore the word "kaivalya" in Shrimad-Bhagavatam 12.13.12 should be interpreted according to these explanations of the true purpose of Shrimad-Bhagavatam.
The true meaning of “kaivalya", then, is "pure love for the Supreme Personality of Godhead".
However, even if the word “kaivalya" is interpreted to mean "purity", it still refers to love for the Supreme Personality of Godhead, for that love is the purest thing that exists (it is established in the Bhakti-sandarbha)
Any materially motivated thing is criticized in the following words of
dharma-projjhita-kaitavo 'tra paramah
"Completely rejecting all religious activities which are materially
motivated, this Bhagavata Purana propounds the highest truth."
Shrila Shridhara Svami comments: pra-çabdena mokñäbhisandhir api
nirastaù "In this verse the preposition
pra' in the word
projjhita' indicates that the desire for liberation is also rejected
in this book."
Therefore this verse of Shrimad-Bhagavatam declares that the desire for liberation is actually materially motivated (kaitava). Although the word "kaivalya" may be used to describe the Supreme Personality of Godhead, or the spiritual nature of the Supreme Personality of Godhead, the devotees who love the Supreme Lord still say (Shrimad-Bhagavatam 3.15.49):
kamam bhavah sva-vrijinair nirayeshu nah stac ceto 'livad yadi nu te
"O Lord, we pray that You let us be born in any hellish condition of
live, just as long as our hearts and minds are always engaged in the
service of Your lotus feet, our words are made beautiful (by speaking
of Your activities) just as tulasi leaves are beautified when offered
to Your lotus feet, and as long as our ears are always filled with the
chanting of Your transcendental qualities."
Here it is seen that the devotees give their love to the Supreme Personality of Godhead alone. If the word “kaivalya" may be interpreted to mean "liberation". Still, the best meaning of that word is "pure love for the Lord". That is the interpretation that should be accepted.
In Shrimad-Bhagavatam (2.3.12) it is said:
kaivalya-sammata-pathas tv atha bhakti-yogah
Shrila Shridhara Svami comments: "This verse means: `Devotional service is the true path of liberation."
The word "pathah" (path) here means "the way to attain association with the Supreme Personality of Godhead."
In truth the word "kaivalya" and other like words primarily refer to pure devotional service/love for God.
The above answer is based on Priti Sandarbha by Jiva Goswami.
Sayjuya is same as ekatvam and is not desired.
In ŚB 3.29.13 it is said,
A pure devotee does not accept any kind of liberation — sālokya,
sārṣṭi, sāmīpya, sārūpya, ekatva — even though they are offered by
the Supreme Personality of Godhead if devoid of My devotional service.
Thus, the essence of Bhagavatam as presented by Gaudiya Vaishnavism is summarised by Srinatha Chakravarti in Chaitanya Mata Manusha commentary to 10th Canto of Bhagavatam as follows:
aradhyo bhagavan vrajesa-tanayas tad-dhama vrndavanam
ramya kacid-upasana vrajavadhu-vargena ya kalpita
srimad-bhagavatam pramanam-amalam prema pumartho mahan
sri caitanya mahaprabhur-matam-idam tatradaro nah parah
It is the conclusive opinion of Sri Chaitanya Maaprabhu that the most
worshipable form of the Lord is that of Sri Krishna, the son of Nanda
Maharaja. Vrindavan-dhäma is the topmost worshipable abode. The
highest and most pleasing type of worship of Krishna is done by the
Vraja gopis. Srimad-bhagavatam is the spotless authority and
krsna-prema is the fifth and highest goal of life.