Attiny85 with Firmata and V-USB

I have an Arduino Uno connected to a mini PC that runs Home Assistant.

Arduino has Firmata loaded and controls some relays through digital output pins.

Just for the fun of it, I’d like to replace Uno with a self-made board with Attiny85 or even Attiny13 and some other components soldered.

I’d like to build my own board and
not use Digikey or some USB adapter.

To connect this new board to Home Assistant it needs to run Firmata and have a software implementation for the USB protocol at the same time.

I think I can load a stripped down Firmata, I’ve also read about V-USB and connecting Attiny95 directly to USB and loading code on it directly. I don’t know if the USB connection will also work for communication from Home Assistant to loaded Firmata.

Is this doable? :slight_smile:
How do I do it?

Nothing? At least tell me this is impossible. :slight_smile: