I think it's a good idea.
My todo list for mysensors is already very long and I have limited time, though, so I don't think I will code this up soon. It shouldn't be very difficult though, so anyone is welcome to have a go and make a pull request. I'll happily review.
https://www.home-assistant.io/components/mysensors/#presentation
Home assistant only supports ethernet gateways that act as servers. So home assistant will connect as the client, ie we only configure the gateway address in home assistant, not the other way around.
If you changed the optimistic setting, actuators will have assumed state and this will show in the ui as two different buttons for on and off.
I recommend to not use optimistic setting, but instead feedback the new state to home assistant.
You need to send/feedback the new state to home assistant from the node in the receive function. Otherwise home assistant thinks the message was not received by the node. This behavior is modified by the optimistic setting in the mysensors config section.
V_IR_RECORD isn't yet supported by home assistant.
I think you will get the best help regarding USB exposure in Hass.io in the Hass.io section of the home assistant community forum.
I'm using hassbian.
Are you using Hass.io?
The config validation when using Hass.io doesn't seem reliable.
I've never used Hass.io so I can't really help you better than this. You can try to search this forum and the home assistant forum for similar questions.
Have you read about the mysensors network?
https://www.mysensors.org/about/network
You need to have basic knowledge of the different parts of a mysensors network before you start configuring the controller.
You should also read about the different gateway options.
https://www.mysensors.org/build/select_gateway
If you know the different parts of the network you will more easily understand how to configure the controller.
This is on my todo list. I hope to get to it soon.
You need to feedback the state change to home assistant by sending the new state from the receive function after the calls to digitalWrite and saveState.