Best way to mqtt publishing a switch in OH3?

[hafniumzinc (T)]

@Nears

Or is there even a more elegant way to publish a switch via MQTT in OH3?

You definitely don’t need to use rules just to send ON/OFF from a Switch Item through the MQTT Binding - you can do this via the native Things Channels - check out steps 4 & 5 here, modifying the topic to suit your setup.