For some reason I thought I saw a post somewhere that said 'move to collection' would also work for reading books to your pet, so long as that pet is your active pet, but I can't find the post again, so I'm not sure if it was a fever dream or not. :' ) Does this work, or do I still need to read books manually?

Maybe you mean Antique Shop? Buying books/food there reads/feeds to active pet. Quick stock or move to collection never worked like that AFAIK.

Ohhh yeah, that's definitely what I meant! I knew I saw something like that somewhere haha. Yeah, I just tried it in quick stock and unfortunately it didn't work. Oh well!