Oh yeah, I built something very similar back in 2019 (app.mirrorspace.net - now dead). Mine also let users post things that were geotagged, and other users coul

Oh yeah, I built something very similar back in 2019 (app.mirrorspace.net - now dead). Mine also let users post things that were geotagged, and other users could only see posts they were physically within 50m of. I actually used it quite extensively during a holiday in Italy and Sicily, very interesting to visit supposedly the same exact places where Roman battles were fought and so on