math without infernal backslashes is one of the reasons I love Typst

What’s the point of switching if you’re going to leave in the worst part?

maybe someone will write a package for latex math

It's called mitex: https://typst.app/universe/package/mitex

Does it support amsmath?

I think so, but I'm no expert in typesetting mathematics.

That's not exactly encouraging... My biggest gripe with typst is the various design choices which make writing maths much harder than LaTeX (and given many of the issues with LaTeX usability come from having to use poorly maintained legacy packages, not having basic functionality in the core of the replacement seems naive at best).