I'm partial to good critter but not universal either. I think non binary people are all very different and there's not going to be one thing.

i, as an enby, like "good puppy"

i dont even generally identify with being a puppy i just like being a good puppy in the kinky way :3 (although, it's not exclusively sexual for me, its generally the praise i like)

other options like "good cutie" are nice

and with partners also things like "good pet" and "good slut" :3

and also with partners "good girl" and "good boy" are okay

Using their name instead of a pronoun probably?