You are correct, it is annoying! Especially when they eat Ro, those jerks!
(Which is to say it's intentionally annoying. The last levels are meant to be more dangerous and tricky!)
Glad to hear you like the game! ❤️ And those are all interesting ideas! Truthfully I don't know how much I can add to the game at this point because the PICO-8 limits how much code or data the game can have, and I already pushed it to its limit. (Past its usual limit technically.) It might be possible if I got even more clever about it.
I can say that with the toilets they explode when they have 10 or more prey put in them, and at the end of each level they heal by 2. So you could for example put 8 prey in a completely fresh toilet and then the next level do 3 more without it exploding. You can tell how far along it is by the smoke / fire coming out. They start smoking at 3 prey and after that each one makes it smoke a little more until there's intense smoke and fire coming out at 9 prey. So it's possible to keep track of it and figure out from a glance how much prey is in there if you learn it. I think I like keeping it that way instead of having a counter to add some challenge and a little uncertainty about it!