I finally made the script I promised to compare how different monospace fonts support math symbols. Here’s the result:
https://mono-math.netlify.app/
This new comparator doesn’t use fallback fonts, so you can see what’s actually included in each font (I realized that my original comparison in Recommendation for a font with good Unicode support? was flawed, because when a symbol is missing from a font the system automatically takes it from another one, so what I was showing there was dependent on the particular fallback fonts that I happen to have on my system).
Looks like JuliaMono has a significant edge 
though Iosevka is pretty good too.