Exactly. Pixels are indivisible quanta, not units of any kind of distance. Saying pixel^2 makes as much sense as counting the number of atoms on the surface of a metal and calling it atoms^2.
Pixels then become containers and subpixels become quantfiable entities within each pixel. In the apple analogy, each crate contains three countable apples and you can count both the crates and the apples independently.
This idea itself breaks down when we get to triangular subpixel rendering, which spans pixels and divides subpixels. But it's also a minor form of optical illusion, so making sense of it is inherently fraught.
