Won't any llvm/gcc supported target get the new version of C automatically? You won't get it in the vendor-modified ancient gcc toolchain for some other arch though.
There are many embedded platforms that do not gcc/llvm based compilers.
Also most companies making those platforms are not good at updating their toolchains. Expecting developers to compile their own toolchain, that is unsupported by platform vendor, is too much to ask.
Also GCC dropped support for certain architectures along the way, and even if you are willing to compile your own toolchain, it may not work for you.
