First I've tried WSL, but firefox can't run it for some reason. Error 0x80110474. Then I've tried using MSYS, but it has an old verion of bash and can't run pass. Finally, I had to use Cygwin with the native GnuPG2 (Cygwin only has gpg1 it seems). Had to modify the pass script to use cygpath when running gpg2.