> Perceived brightness is not at all uniform at equal starting points, it depends on the hue, as well as the saturation.
…but it doesn't mention an (under-discussed) solution available: using a better colour model. OKLCH uses similarly understandable coordinates, "chroma" being roughly the same concept as "saturation", but is designed to avoid just this kind of problem. That is, if you change the "hue" coordinate, you can reasonably expect the perceived lightness and chroma of the resulting colour not to change. Where such a colour does not exist, e.g. a blue with the same lightness and chroma as #FFFF00 yellow, it's simply out of gamut.
There's a colour picker web app[0] that shows the boundaries of the space along with smaller spaces like sRGB, and it's helpful for getting a feel for it. It also links to a post[1] laying out the reasons to use OKLCH in web projects (it's now supported by all three major engines), and the post[2] introducing OKLAB (same space, different coordinate system) is heavy on technical details.
[0]: https://oklch.com/
[1]: https://evilmartians.com/chronicles/oklch-in-css-why-quit-rg...