Thanks for your thoughts. That all sound fair.

I am fine with having quite a bit of configuration on the target device (I am fine with configuration on both sides).

> it ought be possible to make a rpi0 device that outputs a usb-gadget keyboard

I like very much the idea of being able to make the host side (macBook) appear as a usb-gadget keyboard. That way I would just need to plug a single usb cable between the 2 computers. Could you give me a few pointers to get started, to do this on macOS?