Elm is definitely FP and advertises itself as such.
The first sentence of the Elm guide is "Elm is a functional language that compiles to JavaScript" (https://guide.elm-lang.org/).
I'm not sure what your link has to do with FP in the large. It's a Haskell library that aims to de-emphasize point-free programming and emphasize reverse function application over normal function composition. Neither of these choices are defining features of FP (e.g. Scala can't really express point-free programming and method calls are essentially reverse function application, OCaml doesn't have a built-in function composition operator and as a result the community very rarely uses point-free, Haskell generally uses normal function composition, F# generally uses reverse function application, etc.).
FWIW, Elm's standard library has all the operators defined in that library (pipe i.e. reverse function application, reverse function composition) as well as their ordinary Haskell equivalents (forward function application and forward function composition).
