I have been running XCSoar and LK8000 on a Samsung S10e. Both work perfectly and are easy to see even in bright sunlight. On both, I tend to turn off the topo maps and only keep the airspace maps displayed. I have also been using an older LG G6 and tend to use it when flying. The screen is a similar size although perhaps not as bright. I just prefer not to drain the battery on my primary phone (the Samsung) in case I actually need to make a call.

The key thing with the Samsung Sxx as well as the LG Gxx phones is they have built-in barometers (rather than just using GPS altitude). This is actually the first thing I enquire about when shopping for new phones - much to the confusion of the salespeople who really have no idea why that is a deal-breaker if not present.

Clinton
LAK12