Four years after GTK2 was declared end of life, KaOS has finally been able to remove it from the repositories.
The one application that required to keep GTK2 in was Ardour, but with 8.4.0, they ship an internal YTK, no longer needing GTK2.
That left one application still using GTK2, Pidgin. Pidgin 2.14.13 is now build without GUI support, so it no longer needs GTK2 either, that makes the app pretty useless though.

Do you see a need to add multi-protocol messaging client? Or is the current selection enough, with Kaidan as a simple multi-protocol option, and other messaging clients available with a single protocol (like IRC clients, Telegram-desktop, Signal-desktop, Neochat, etc)?

    demm I don't think Kaidan is a good alternative, as it doesn't support group chats for example.

    Anyway I don't see the need for other clients considering they can be installed via flatpak by the few users who really need them. I followed the pidgin project for few months as they are developing an interesting v3.0 but TBH I see very low interest by the users.
    I can be wrong as I'm not expert in messaging platforms, but IMHO the actual KaOS repository is fine also without pidgin v2

    Pidgin 3.0 was checked, but not an option at all (it would be have been added otherwise as a git build), it requires a good bit from the Gnome desktop (it will be completely Adwaita based).