Smartphones [ Edit ]
On the more pragmatic side, Android is based on Linux kernel and when you remove all the Google's crap, the result is not really that bad. That's pretty much what you get with LineageOS (supported devices) or GrapheneOS (only Pixel devices); but keep in mind that those solution still keep a lot of proprietary blobs.
Replicant is a more pure alternative, but it only works on older devices (supported devices).
See also: Android_Apps