Looking at interfaces definition and snapd code, there’s no interface for these sysfs interfaces:
axp20x sysfs interface: /sys/power/axp_pmu/ac/connected
Non-standard interface and requires a patch.
Thermal interface: /sys/class/thermal/thermal_zone0/temp
It makes sense to request a new interface for thermal as it is standard, but not for the first one…
Do you have plans to allow this thru gadget as it is hardware related ?