I have actually been doing some of this in my area for crabapple trees. Not necessarily to eat them, but I find it useful to clean up the sidewalk and dump the fallen crabapples in my compost. IMO it just needs a viewer that focuses on plants that bear fruit, and potentially a tag to designate public access (maybe just reuse access:public).
There's lot of people mapping such details in OSM already:
https://wiki.openstreetmap.org/wiki/Tag:natural%3Dtree