gdm-settings VS Gradience

There is gdm settings https://github.com/gdm-settings/gdm-settings I have not used it a lot, so no idea if it can do what you are asking for.

AFAIK this allows you to mirror current user settings to the gdm session: https://github.com/gdm-settings/gdm-settings

You can use GDM Settings to modify the Login screen.

Use some utility like Login Manager (be aware that it may break things, specially on distros with custom GDM settings like Pop)

Or, going by this screenshot, you could apparently use the Login Manager Settings application as well.

You can use Login Manager Settings to both extract and modify the shell theme/css.

I currently have used / use https://github.com/realmazharhussain/gdm-settings . works like a dream

To theme the display manager i don’t know of manual way but there is this app

If your main problem with Adwaita are the colors, you can easily customize them, and there are even great GUI tools for this[1]

My issue with Breeze aren't the default colors, but rather the theme itself

[1]: https://github.com/GradienceTeam/Gradience

I really like GTK4 / Adwaita and dislike the look and feel of QT, but I guess that's just personal preference.

You can change the colors of Adwaita using https://github.com/GradienceTeam/Gradience it even has a mode to extract colors from your background like current android versions

Application Theme : adw-gtk-3 with Gradience

This might be an alternative for now - https://github.com/GradienceTeam/Gradience

if the app is using libadwaita you cannot modify the css, you can use gradience to set custom colours though, but it is not the same as modifying the css

For everything else I use the only tool available for properly configuring GNOME: dconf-editor. At this transitional time, managing themes is a challenge, but I like Gradience.

You could also use themix or Gradience

Try https://github.com/GradienceTeam/Gradience/ .

You've tried Nord from Gradience ?