Cell phone gps application do not collect the amount of information that a $70 Bryton Rider 15 neo unit collects, and will upload to various websites that keep track of your rides.
Any reliable usb 10000mah power bank will provide all the electric needs for 36 hour ultra cycling electric needs, including gps units and cell phone charging needs while on your bicycle...
Solar power for GPS units should be a simple inexpensive upgrade by all manufacturers, but in the meantime a power bank can keep your Gopro, Insta360, Cell phone and Gps units properly charged...
Have you ever monitored the power used by your phone running a GPS application?
Occasionally I do use my Garmin Instinct when I have to track runs or bike rides. These trackings aren't to be posted on Strava but primarily keep folks where I am especially when I am biking/travelling alone. My friend has the same Garmin Instinct but the Solar version. For a fact, I know he was having issues and glitches where it would track intermittently or inaccurately. So I am a bit unsure how useful solar is if it's this unreliable..:-(
My non-solar Garmin has been pretty reliable..