Non-theme plugins can register setting schema for plugin settings. They show up under Settings > Plugins.
Request the same for the theme plugins. This will enable theme designers to give flexibility to their themes with options like customizing the accent color, hiding/showing specific elements or changing colors for specific items of importance.
Currently, it is possible to access theme settings from the Installed Plugin page > Themes tab > choose “Open Settings” from the dropdown of a theme (if the theme has registered settingsSchema just like non-theme plugins)
I can look into contributing to this but need the opinion of others in the community before I proceed.
Edit: added images for reference