Are there GPS devices that use non-proprietary software and connector? Ideally USB C for the connector. I've been using my Android phone with GPS Essentials and am frustrated by the constant dropping of tracking by the software.
Garmin used to make a unit called the Monterra, which sounds like what you're after: it has a mini-USB port, runs on Android and you can install other apps on it from the Google Play store. I don't think they make them anymore and as far as I can tell none of their current units offer the ability to install your own apps on them, though most of their current units have USB ports. I think they've stuck with mini-USB ports because the port is more sturdy than micro-USB. USB Type-C is still very new, I don't think we'll be seeing it in outdoorsy GPS units for a while.
If you just need a better GPS location on your phone, you can keep your current phone and get a bluetooth-enabled GPS receiver like the Garmin GLO, Bad Elf, or Dual XGPS.