I have been having some fun with this project over the weekend. @0xd61 meta-picocalc is a great repo..really got things off to the races. This is the way forward IMO.
Among a ton of other small quality fixes and adding meta-rtlwifi support, I refactored the picocalc_kbd driver into a mfd device with peripherals. I have battery, backlight, and keyboard backlight drivers now. I’ll get my work posted to github as soon as i can get things in a little more stable state.
root@luckfox-lyra:~# cat /sys/class/power_supply/picocalc/capacity
100
root@luckfox-lyra:~# cat /sys/class/power_supply/picocalc/status
Full