It’s great for plants! I always used ours. Sometimes I added it around plants and sometimes I added a few “ rabbit M&Ms “ to a jug of water, let it ferment a bit and used it to water potted plants on the back deck. I did also dump some in the mulch pile. It composted pretty quickly. I always used non bleached paper bedding for her litter box.
We have community composting here and I wasn't sure if I could compost our litter, (woodstove pellets), so I stopped by this week to ask. They said that rabbit poop and wet woodstove pellets are fine for compost, but also mentioned that other animal droppings aren't compostable because they have bad bacteria.