If I wanted to get into linux phone development, what's a good entry point into this?
2. Find good programs on https://linmobapps.frama.io/
3. Figure out what functionality you're missing. Contribute improvements.
Keep in touch with the community at https://linmob.net/
Linux phone development is more or less the same as linux development, just with a computer that has a smaller screen and a modem.
Sometimes it lasts 36h on a single charge when in standby, and sometimes a fraction of that. I cannot trust it to last me a whole day without a charger.
Other older phones that I tried last year (ranging from very old Nokia's to Blackberries with 3G) all had issues with call quality and even with random signal loss. I couldn't reliably stay connected with my family, which frustrated everyone.
Your application/mobile OS likely uses mobile data in some fashion, definitely uses up some CPU cycles (in foreground or background), may trigger high-powered modes in the cell radio through its usage patterns, or might miss incoming messages entirely. Testing on real untethered hardware, even as a final check, is needed to see that what you built isn't a frustrating paperweight that cannot fulfill the function of a phone.
It's a UI Framework being used to make the basic OS apps in a fully scalable form. They're currently used in Plasma Mobile.