I can help help testing with the Shelly Pro Dimmer 2 PM.
I have installed “org.openhab.binding.shelly-5.1.0-SNAPSHOT-dimmer.jar”. Devices were autodetected after a device-reboot.
The channels in the “Dimmer” group are only working in one direction. I can controll the dimmer from openHAB but the items are not updated or stay NULL if I control the dimmer via wall-switch or shelly app.
All other channels seem to work fine so far.