Comment 9 for bug 1960702

There are two problems:

$ fish_add_path -aP $snap_bin_path
which breaks the fish script startup as the fish_add_path needs a higher fish version than 3.1

and a wrong XDG_DATA_DIRS separator (empty space instead of ':')
$ set XDG_DATA_DIRS $XDG_DATA_DIRS $snap_xdg_path
This prevents snap apps from being found in the launcher

The first problem can be fixed by adding the fish ppa to upgrade fish as suggested here: https://askubuntu.com/questions/1392178/where-should-i-find-the-fish-add-path-command

The second can be fixed locally by replacing
set XDG_DATA_DIRS $XDG_DATA_DIRS $snap_xdg_path
by
set XDG_DATA_DIRS $XDG_DATA_DIRS:$snap_xdg_path
in /usr/share/fish/vendor_conf.d/snapd.fish