Not an answer really, but I hope an extra data point helps. I'm using Nim 2.0.0 in VS Code (1.82.2) with Nim extension (the one by nimsaem) on MacOS (Darwin 22.5) and the "Go to Definition"works as intended.
I switched using choosenim to nim 2.0.0 and it works. :-( Weird. Maybe because I installed before that nim 2.0.0 using a package manager instead of choosenim? case closed.