I think that having to jump back and forth between the collection and Pokemon pocket every time to add cards one by one feels a bit slow and clunky.
I think it would be more convenient if there was a dedicated “Pack Opening” entry tab where you could add a full pack of cards on one screen before saving them. A quick-add feature like that would make it so much faster for to keep cards up to date.
Have you tried screenshots and using the scan feature? That seems to work well for me. Every once in a while, it will have an incorrect match, but you can choose which ones you want to update and then just do the incorrect one manually.
The scan feature works well and is super cool. For someone like me who has completed a few sets it would be nice if there was a way to instantly set every card in a set to at least 1 quantity. Even if I’m missing like 10 cards it would be easier to set a whole set as quantity 1 then go through and remove the cards I don’t have.