Hello @guyr,
I did notice your mention of version 24.04.
What I outlined still applies as a method to roll in what they have as a theme, directly from the GitHub repository, if they can confirm that the theme itself is 24.04-ready, even if not rolled out as part of the official release for some reason (possible oversight?). I tried that myself for another theme, but that one appears to have definite issues.
According to this other posting, GTK4 has been out since 2020, so it is possible that the gtk4-compatible version is good to go.
Also, the tracker site messaging for the gtk-4.0 doesn't seem to have anything that says that the gtk-4.0 "components" have been "bumped off" for bugs or other technical issues.
But I agree it would be a go/no-go criterion to get an actual confirmation from either of @Frieder_Saugschmerle or @raveit65.