I'm eagerly waiting for the day when it becomes impossible to make any sort of customisation at all in GNOME/GTK apps besides what the app developer intends. Now that user themes have been axed, I hope fonts, font size, and icons are axed as well and Adwaita, Cantarell (that's the default GNOME font right?), and GNOME Icons are enforced everywhere. It certainly won't be surprising for me if this happens and things seem to headed in this direction.
I'm sorry to see that Jeremy still hasn't figured out that GNOME/GTK isn't a community project and is still trying to engage with their devs about themes even though the recoloring API page clearly says that system themes won't be supported.
> for example KDE apps should run just fine inside GNOME, and vice versa
Yeah, I doubt that. Even if somehow it does look fine right now, I don't think it will soon.
https://gitlab.gnome.org/GNOME/gtk/-/issues/3409
> I don't have any comments on the file chooser, anything we say is flogging a dead horse.
Yeah, I know. It's pointless to have discussions, especially when the project in question isn't a community project and follows the "look but don't touch" open source model of development.