I was looking at the Pi 400 and was planning to buy it to tinker around with. I also have another pc that I use and don’t want to use separate keyboards for each system and was wondering. Could I use the Pi 400 as a keyboard for my pc as well as how it was intended to be used.
Doesn’t look like it. I’ve not tried it, but I have two ideas;
configure the Raspberry Pi as a USB device emulating a keyboard, and write or find software that will receive keyboard events from the local keyboard and transmit them over USB to the PC; budget about 20 hours work for an expert,
run a screen sharing application on the PC that can receive connections from the Raspberry Pi.
Hope that helps!