And just to add, the most durable thing that Elm has contributed to the frontend world is TEA, The Elm Architecture, upon which most reactive libraries and frameworks now sit, such as React, Flutter, Vue, Angular etc; UI is a function of State.
It’s also a relatively modest extension of decades of prior art so I think it might be more accurate to treat it as a formalization of that practice rather than implying it was foundational.
Looking at the language used to describe it on https://guide.elm-lang.org/architecture/ I’m struck by the resemblance to the message-passing systems which were common in the 90s and 80s due to the influence Smalltalk had in the 70s.