function _project_dirs
  string replace -r "$REPO_HOME/(.*)/" '$1' $REPO_HOME/*/*/
end

complete -c project -a '(_project_dirs)'

function _project_dirs
  string replace -r "$REPO_HOME/(.*)/" '$1' $REPO_HOME/*/*/
end

complete --command project --arguments '(_project_dirs)'

Stop using short option names
Stop using short option names

lee-dohm/dotfiles,lee-dohm/dotfiles,lee-dohm/dotfiles,lee-dohm/dotfiles