I built something I think this community would find useful
Hey everyone, I asked the mods and they're OK with me posting this.
I spend a lot of time on multi-day trips and hikes, and after enough bad situations with no signal I realised I needed an app that didn't exist. So I built LastBar.
It's a free app that maps real mobile coverage as you drive or hike, and combines that with signal maps from other users. When you're stuck with no signal, it points you to the nearest place your phone will work, and to the nearest water, shelter, clinic, police station or fuel, all offline. There's no account, no sign-in, and it only uses about 3% battery a day.
Android phones build most of the map, since iOS limits what the app can read in the background, but iPhone users can still see coverage data captured by other users and find signal based on that and cell tower locations.
The app is still new so the map is empty where nobody has been with it yet, but every drive, walk, or hike fills in the map for the next person. If you're planning an outing soon, I'd love for you to try it out and let me know what you think!
There's more info at https://lastbar.online/ if you'd like to take a look.
Android: https://play.google.com/store/apps/details?id=agency.clc.lastbar