What would you recommended first? I'm also self-taught, just JavaScript, typescript and react and a tiny bit of shell scripting. Job never asks for anything more, but I want to get better at designing, engineering, and building scaleable webapps. So more towards "full stack" I guess.

Haskell sounds super cool, but it seems like nobody really uses it to build things on the web. They mostly just talk about how it "helped them think".