OSC over USB

yes, starting in 2.6, but the details haven't been published yet. i guess that will be added to the show control user guide

That sounds nice, I hope the developers will give us an example for arduino.

It seems there is a small hardware project with arduino on ETC Labs. I will check it the next week.

Yes there is. It comes with instruction, a list of parts needed and an Arduino sketch

FWIW, I'm doing this with a Pi Zero using USB-OTG networking. The Pi boots as an RNDIS network device. It takes a little finagling depending on your host OS to sort out the drivers and network settings.

It works with WIN 10 (on macOS Sierra with Parallels) but not on macOS itself. Maybe that is something missing in
the mac version of ETCnomad?

OSC over USB is currently not supported on Mac.