pamac is gtk.
And its the only graphical package manager manjaro suggests or supports.
The nomenclature as of now is pamac-gtk and pamac-gtk3, with the second being the ‘classic’ one developed up til now. pamac-gtk is current and gtk-4 and notably libadwaita specifically. While that is probably best integrated with Gnome … its not gnome-specific. Any desktop that can handle gtk4 can handle the new pamac.
It may make sense for the team to decide to include one or the other in certain editions … but it is not a requirement … may be undesirable because of pamac-gtk3s near frozen state … and reflexive of a change that has only recently occurred, with there being no curated big ISO release since then. So if they want to make that change … it isnt so unreasonable for it to just not have happened yet.
Or … you know … skip pamac altogether and use pacman as Arch intended.
(with Octopi as a graphical frontend if you absolutely must)