$ snap list --all
No snaps are installed yet. Try 'snap install hello-world'.

sudo snap install firefox
$ snap list --all
Name Version Rev Tracking Publisher Notes
bare 1.0 5 latest/stable canonical✓ base
core22 20230801 864 latest/stable canonical✓ base
firefox 117.0-2 3068 latest/stable mozilla✓ -
gnome-42-2204 0+git.ff35a85 126 latest/stable canonical✓ -
gtk-common-themes 0.1-81-g442e511 1535 latest/stable canonical✓ -
snapd 2.60.3 20092 latest/stable canonical✓ snapd

firefoxをインストールしたらgnomeとgtk-common-themesが入るから
snapアプリが利用するためのsnap環境で必要みたいだね