Multiple Mysensors gateways

does openhap Mysensors binding support multiple gateways?

Not sure…
Worth a try.
The gateway are a thing to be added via either paperUI or file
You may be able to add several bridges

If it doesn’t work you can always post a feature request there:

I can’t see a MySensors Binding. Is this a market place Addon?

Yes it is.
I got it working but it has a fundamental flaw.
When on discovery mode it discovers the different nodes but creates a thing for each sensor instead of a thing for the node and a channel for each sensor. It created too many things and was quite unmanageable.
I use mysensors with MQTT and a “topic translator” in node-red