If only that were a practical solution. The open-source community doesn't have everything, sadly, and some of the best applications are only available in the Play Store, behind a pay wall.
I like drawing and note-taking with my S-Pen enabled tablet. There's no good open-source alternative to Artflow or Nebo (both paid apps).
Sure, you could pirate it... even with morality aside, I'd rather trust Google than random APKs acquired from the dark corners of the Internet.
And with this setup, Google doesn't really have much information about my person, so I don't care if they have info on the device (assuming you take proper steps to keep the device anonymous).
It is occasionally realistic, depending on your use case. The open source situation on Android is not nearly as lamentable these past couple of years compared to earlier. In the context of specialist paid software and hardware, it's of course less likely to be possible.