It's all open and so should be able to work with OpenHAB as well but it would need somebody to either write a firmware that's compatibale with the OpenHAB endpoints or add ESPHome interegeation into OpenHAB. Somebody might have already done that for their voice stuff. There is not much yaml in home assistant now unless you want it. I'd give it a go in a VM and see what it finds on your network :)