Remember the size of the original iPhone? I have long wondered why nobody makes a universal compute brick in such a form factor without a screen. Then sell 5" or 7" or 10" or 27" screens with and without touch that connect to the little brick.

I can buy a 15" screen right now for under $75. It's the ultimate super-thin laptop if you remove the compute and keep the brick in your purse/backpack/holster.

For extra points, connect two compute bricks for more muscle.

Thermals is why. Closest we get is Mac Mini and NUC.

The UI elements on iPadOS are necessarily larger to accommodate touch.

It's just a lot less information dense than macOS, and making it the same scale will make using it as a touch device harder.

I mean, Samsung has DeX. It’s exactly what you describe. I don’t like it, I don’t need it. I’d rather have a focused device than one that tries to be two things at once.