The “don’t theme my app” thing just tells me that GNOME/GTK+/Adwaita aren’t built in a way that gracefully handles theming, or that devs building apps with them are doing things like hard coding colors when they should be using dynamic system colors such as those provided by UIColor[0] in UIKit.
[0]: https://developer.apple.com/documentation/uikit/uicolor/ui_e...