@thomas166 So there few components to your requirements. The first is that you don't want to have the firmware misimatch issue. The only solution to that is you need to that is to create a DTS for the lte, since sysupgrade reads the device type from from /tmp/bard.json and /etc/board.json, these are created when the device tree is loaded, so you need to create a dts with the correct identifier in it. Here is a link to a patch I created that will add the lte device and include the lte-base in the build. This is a patch for OpenWrt 23.05.3 so you may have to merge it in manually.

@SpiderKenny Yes fastgpio is better but I showed code that uses the file system instead as I'm not sure of your level of experience and this method is easy to implement.

I saw the dock a couple of weeks ago, seems like a good idea but personally I prefer discreet functional expansions.

@crispyoz UCI defaults is a special directory where you can drop scripts to do initial device setups or configurations on first boot.

@Chris-Drake I've tried it too.