Also make it maintain 2 cursor positions and switch between them depending on the mouse. It would be pretty neat with multiple monitors, with focus following the (active) cursor. (Assuming you're ambidextrous, of course :))
The steam deck has a keyboard that supports input from both trackpads at the same time. Always surprised me this is not really supported by most desktop environments.
In 30yrs of IT support, this is a thing I have never seen. If I had, I'd be forever inserting into conversations about end-users. Strictly for the novelty.