The lang is still under development, the most current in in Fortran 2023:
https://global.oup.com/academic/product/modern-fortran-expla...
A bit like C23 and C++23 are here, and the large majority is a mix of C89, C99, C++11, and C++17, as what folks in the trenches care about.
Or Java 8 versus Java 24, and so on.
Fortran is in a similar position.
Also we have one use case that is responsible for OpenCL losing mindshare for scientific community, running Fortran on GPU.
Thus I bet at least Intel, NVidia, AMD, Cray, IBM, being relevant ones.
Yes, some of them are planning to eventually adopt LFortran to replace their own, like they did with clang, or at least are using LLVM nowadays.