I agree, the first two problems are rather easy to solve with phonetrack or any other of the tracking apps like µlogger, Owntracks, Traccar, etc. and nextcloud or the backend you provided. What is the reason that the simple heatmap is not ideal? Does it also lag or are you looking for filters functionality, etc.? The data pre processing must be challenging cause thats the part really seperating the self hosted solutions to Google’s one. If one could pre process the data on a nextcloud server and could render it on a map without significant lags, that would be really cool. Maybe I’ll try to work on that in the future when I got more advanced in programming.