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.

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.