Yes this is not an easy problem to solve. Unfortunately I’ve not seen a way to configure a device without some custom per-device config.
In my opinion the best way to do this is to create a custom conf.json file (say conf2.json) file for every single device on your network.
This way you can have a single firmware and then just upload a specific conf2.json file to your device with the
From this point on flashing your device with
mos flash will remove the conf2.json file, so from this point on the best thing to do is to flash with OTA update which will preserve the
I asked a similar question a little while back here