About to migrate from HomeAssistant: what should I pay attention to?

thanks again for the helpful insights. I am going to install debian and then openHAB, all inside a VM for testing.

Just as info, I recently moved my OH to docker, I use a zigbee USB dongle. So far it works pretty ok to me and I would actually recommend it. I am using --device to access the hw serial port.
I did not look at how to call any external scripts, but I am pretty happy of the docker solution in my case.

thanks for the info. When I feel comfortable with OH perhaps I will probably try the docker route, since I am aware of the benefits of Docker.

In the learning phase I try to keep things as simple and easy as possible. I find the VM route ok for this purpose: I can make a snapshot before every move and revert in a few seconds if something goes wrong.