ārto jijñāsur arthārthī jñānī cha bharatarṣhabha
distressed, the seekers of knowledge, the seekers of worldly possessions, and those who are situated in knowledge.
(Gita 7.16,Swami Mukundananda)
speaks of 4 classes of devotees ( comprising of sakama/nishkama bhaktas) , who are in the different rungs of the same ascent.. Nishkama jnani bhakta who is in constant union /have completely yielded to divine alone , is truly superior than a Sakama bhakta who have nt crossed the world of duality , Although a Sakama pray for material benefits, their act of seeking divine itself is regarded noble . bcos this attitude of seeking would help them progress in the ascent.So they too are lauded in Gita, udārāḥ sarva evaite (
All those who are devoted to Me are indeed noble) irrespective of sakama / nishkama says Gitacharya.
A Jiva is entitled to do karma only in manushya loka , Karma is not possible elsewhere (as a pashu , pakshi or Deva etc) karmānubandhīni manuṣhya-loke(BG 15.2).. So In order to perform any yajna , homa or Puja etc , even celestial may ve come to manushya loka .(as per several instances in various puranas)
A puja is definitely a virtuous act( done in shaastric way,though a Sakama devotion ),which is always preceded by a sankalpa comprising it's purpose . Sankalpa procedure standardizes Parameshwara preethyartham and the result of the puja is bhakta anugraha by Parameshwara.It enables one become a vessel for divine grace apart from fulfilment of material wishes.(Etymology of पू is to make pure, cleanse, purify,and that of Ja is sprung from , born . So performing Puja enriches purity of mind .)
Sheer recital of Shiva Aparadha Kshamapana Stotram,Rama nama, Gayathri mantra / certain rites, can mitigate the effect of sins (expiation),..This however does not mean the karma doctrine is refuted , as it is believed that any janma had occured only bcos of karma .. Puja is again a karma whose Karma Phala is positive with divine grace, so it should not be overlooked as some thing inferior as long as one hasn't crossed the duality.