Why does the chromaticity diagram look like that?

I think a good explanation of color spaces might be starting at a camera sensor with a bayer array and how that’s processed.

I'm not so sure.

I think it's really important to understand spectral colors and metamerism.

If you start at the Bayer array, you are going to have an odd discussion about how the bayer filters have spectral transfer functions that aren't directly related to the cones in our eyes, nor any color space's primaries, etc.

It's going in the deep end.

Starting with the function of the human eye seems like a good choice, I mean how else would you explain why a Bayer matrix only has 3 colours?

Or why there are two green pixels in the Bayer pattern for every red and blue...

I was imagining a more simultaneous exploration of bayer matrices, human eyes, and color. For example, that question of why 3 colors, or why 2 green pixels, opens the door effectively to a lot of ideas.