https://community.home-assistant.io/t/eq3cli-not-found-hass-os-5-12-docker-19-03-13/287755
Try this line above that worked for them. When you have bluetoothctl running you can type help and it will show you all the commands. Pair is one of them. It will connect for a min or so and then disconnect. This isn’t necessary but at least you will try it and it’s what I tried when I first got an eq3. I created a little switch to restart the bluetooth on my HA as at the time I was tinkering with HA alot and got fed up with having to type in ssh each time eq3 became unavailable.