I'm collecting minions and saw that other collections (beanbags, cards, etc) have a way to view uncollected items. Is there a way to do this with minions?

The minion zoo is different from the other collections (no achievements, items are removable, etc.) so I assume that's why the functionality isn't there. You can create an account on Subetalodge and update your collection list over there though to easily see what's missing.

You could also add the missing minions to your wishlist if you don't want to keep updating the Subetalodge list in the future, but that might be a little bit tedious starting out

I don't mind using external sites so that'll be helpful, thank you! Hopefully one day they can add missing pet functions to the zoo.