How hard it is to get a "compiler job" depends on what you mean. Getting hired by Apple to work on the internals of the Swift compiler is very difficult. Especially if you are not an American citizen. However, getting a job developing parsers/compilers/transpilers in lesser well-known companies might be considerably easier.

Hoping to get hired by a FAANG company by hacking llvm is essentially the same as trying to get a record contract by busking in the streets. I mean it happens if you are exceptionally talented, exceptionally hard-working, and exceptionally lucky, but it is very, very rare.