I'd have to look into it. Off the top of my head maybe apps can track via wallpapers but a higher risk online with websites/webapps would be things like screen size, resolution, user-agent and settings like prefer-darkmode etc.

I suppose it makes sense that if someone were to really hack away at their environment have have a lot of uncommon settings everywhere it makes them more unique and easier to fingerprint depending on the settings and whether it's exposed to and read by the web.

Maybe that's why GrapheneOS comes with a plain black wallpaper by default.