Hector Martin

You probably want model paint then, it comes in lots of bright colors, albeit in small doses

Hmm, thanks for the suggestion… I don’t know much about paint, but it seems to be hard to find actual color values online in a lot of cases

Colorimetry is hard. The mapping depends on way too many factors (e.g. what light you use), even if you assume sRGB on the RGB side. An unqualified RGB tuple is almost meaningless.

Colorimetry is hard, sure, but the difference I’m talking about is large enough that it doesn’t really matter.

The reason why there's no paint in pure sRGB corner colors is probably that it'd be too dark in normal lighting. If you only reflect a very narrow band of wavelengths as required, you're throwing away most of the spectrum. Things are always duller in reflective media.

There's probably a way to do the math too. Assuming a D65 illuminant, there should be an optimal reflective response that visually matches an sRGB blue primary chromaticity, and then you can calculate its brightness relative to 100% white. I'm sure it's less than #00f/#fff.

More like a curve of visual closeness vs. brightness, no?

Well, you could compute a 3D space of the optimal spectra representing a chromaticity from 100% sRGB blue to white, and then pick the one that matches the brightness of 100%B in sRGB (which will be washed out)