Base Android (AOSP) is not, what you probably mean is Google Android.
Look at GrapheneOS, that is a usable, privacy-focused Android without bloat.
I’ve used it for many years. Lineageos is a largest rom sure .
The issue is that google fucks with base android more and more. Now they made it that there is that yellow logo on boot - your android is insecure. Then banking apps are not working.
Updating from android to android on lineage was a chore on oneplus 8t.
And I ended up not being able to rollback to stock because I wanted to trade in for A new model.
It just makes it harder to use roms.
Almost none of the devices are shipped with anything but Google’s Android, and manufacturers don’t provide you alternative versions of Android
Yes, Google owns Android as a whole, but (almost?) every single OEM customizes Android for their purposes. That is not the same thing.