I just put an appropriately-sized cardboard box on the corner of my desk.

Ditto, a short box from wet cat food worked really well to keep my cats off the laptop.

I have a USB keyboard and external monitors, so the laptop sits off to the side, and is warm, so they loved to sleep there. Particularly a problem since it also has a button that powers off the laptop. I made a keyboard cover, but even then it was problematic with them sleeping on it (thermal throttling).

Putting a box on the desk solved that, they prefer it, until a second cat wants to join the party, which is thankfully rare.