I've finally added a nice little feature to the mathstodon.xyz web frontend: while you're typing, LaTeX math macros will be replaced with the corresponding unicode character.
So I can write something like "the area of a circle of radius 3 is π × 3²" very easily!
MathJax still works, between the delimiters: \( π \times 3^2 \)
Another benefit: doesn't look like total bums to people on non-MathJax-y instances
... and now I've made it not replace macros between LaTeX delimiters, so stuff like \(x^2\) works without faffing about