@JoseVigil this is very meta .... don't expect we get the whole idea ... do you have more real examples what it could be used for?

I try to understand what I could do with a second/third/fourth input device. And if I don't have multiple input devices, do I loose some features I have with them?

A example I could image: To switch the showed console on the monitor to another VM via the smartphone. But that's too simple for a real world scenario

Or do you have in mind to control the inner things of a VM via the "input devices"? ... hmm...

Edit:
Patents? Really? XCP-ng is a open source project... We don't want to do things to make money with proprietary things/technology. We want to enable users to use XCP-ng. I don't get your point.

Disclamer: This all is my personal opinion. I'm only a community member and can not speak for the whole project. If you want to have more official answers, contact the project founder @olivierlambert