There are open source alternatives available (e.g. on F-Droid). So I don't see why this is such a big issue.
Google is slowly but surely turning more and more components of Android into closed source code. This is a targeted effort to kill AOSP and lock consumers into their ecosystem. The end result will probably look a lot like macOS: a few open source parts, but primarily a proprietary stack.
What? Just checkout the sources and go through them, maybe?
> not having properly supported open source apps is not the best
If your definition of "properly supported" means "supported by Google", I guess...
I think you misread my comment, or I wasn't clear enough, I work on AOSP daily so I know very well what's in there :)