Yes people do keep mice, usually not wild ones, but there really is not much different except you have to work much harder to make them handleable and tame. I don't have any mice, so I don't think it would be good for him to come here. You could start looking now for a pet owner who would add him to their family, it won't be too easy but you can try.
I did release the baby mice I fostered. I caught them in my house and kept them until they were big enough to survive on their own, and started making them work hard for their food by hiding natural foods (like seeds, bugs, etc) in their enclosure under things and in little mounds of grass. I took them out in the countryside -in Surry- and released them together in a cornfield, they were not tame and were terrified of me, though.