Commands to copy overlay to extroot during first boot OpenWrt/Domoticz build (Solved)

is it i2c?... generally python / c is used ... the latter being more lightweight.

you could also interface via a micro-over-usb-serial. this has the advantage of many many more gpio... but the middleware can be time consuming. or pcf then 433... works nicely too.

here is an example of python i2c