True. The alt text in my case contains the LaTeX which contains all the information to define the equation. But you're right that a standard like MathML would allow for other surfaces like Braille.
The way I have it set up in my use case is that if you click on the equation it switches to a brief description of what the equation is doing. Pretty useful for quickly parsing it for someone unfamiliar.
Check out Pretext, it's write once, read anywhere software package that supports cross platform publication output including Braille [1],[2].
It's a very powerful authoring and publication system, for example if you're writing an interactive Math book, you could use <sage/> blocks to specify language e.g. Python, write around code blocks, providing references to equations, etc [3].
Fun facts, PreTeXt was originally called MathBook XML thus it has robust support for mathematical formulas [4],[5].
Last but not least, don't let XML being used in Pretext scared you off since XML is great for markup language and anything todo with publication online, printed, Braille, etc [6].
