I think it would be nice to be able to use multiple items at once. For instance, mushrooms, mana, health, etc. It gets really inconvenient around level 25 to click I don't know how many times to get your 2000+ health pet back up to full with mushrooms. I'm sure others have suggested this, but I thought I'd throw it out there.

Some fest items have had this feature added, and it's been pretty convenient.

Notably, though, it does cause some issues for mobile players, who can't split stacks... so there would need to be some balance so somebody didn't accidentally use an entire stack of elixirs on one pet.

But it would definitely be useful in the future, I think, with the right balances.

Yeah having to use click many mushrooms for how many times gets really annoying.

I was about to suggest something similar. It's kind of annoying having to open the mission satchel one at a time, especially if you have a whole bunch of pets doing missions. (It's only kind of annoying right now because I only have three mission pets. I'm sure it'll get worse once I get further along and can send more pets out at once.) Full support.