When I encountered these they were maintaned by a community or space like houseprojects, collectives or free shops. Some seemed to be accessible all around the clock and some just when the space was open. So its not just a fridge standing around but actual groups/people caring for it.

I dont know if the places were connected to the food-sharing network, but some probably were. Here is a wiki entry about that https://en.m.wikipedia.org/wiki/Foodsharing.de

Sounds like a standard office fridge.

I think there could be inspections done regularly (every week or month) by the owner of the fridge or by other people (depending on your idea of how the fridge should operate)

I’d rather I didn’t.