Nice post! I love hacking around with PostGIS. While I'm not normally a huge ORM advocate I do like the GeoDjango API for this sort of thing [0].
There hasn't been enough experimentation with geospatial social applications. (There was a lot back in the early 2010s but it petered out.) I'm currently working on an experimental chat app that creates Slack-like channels associated with a topic and a location. I'm looking for collaborators on this project (primary need is for designers and community-builders, but also programmers) so if it appeals to you please get in touch (HN-facing email in profile).