Compostable Toilet Advice Please

We're renovating our old shed in our back yard in Michigan and turning the shed into a tiny garden house. There will be electricity, heat, and air conditioning but no water/plumbing. We're thinking of putting in a compostable toilet. Does anyone have any advice on the type to purchase, trade-offs, and anything else I should be thinking about before we buy one. I read online that for some of them you need electricity and a vent to the outside. It won't get used much at all, but we'll be happy to have it when someone needs it. Thanks.