I really appreciate this work. I realized how important it is the other day when I needed a text editor on my phone and realized how opaque the Play store is, it's hard to find an app you can trust not to hoover your data.
Either you give a closed source app access to your files, or it saves your notes to it's cloud. Even apps that are open source aren't transparent as they haven't necessarily uploaded the version in github. So it all falls apart and you're back to plain old trust so long as you use the app stores.
Have you tried F-Droid as a primary source for Android apps?
They include only open source apps, rebuild the app from sources themselves, list possible anti features in app description and does not allow apps with tracking in their catalogs.
I have much higher trust for anything I install from F-Droid in comparison to Play Store.
As for text editor I use Markor [1] and it is rather good.
Either you give a closed source app access to your files, or it saves your notes to it's cloud. Even apps that are open source aren't transparent as they haven't necessarily uploaded the version in github. So it all falls apart and you're back to plain old trust so long as you use the app stores.