Saber notes is really good. It's more for notes, annotating PDFs and simple artwork than anything graphic design level though.
It's currently in early development and I don't know how well it works, but Xournal++ mobile is a thing. Its desktop app is really good, so I'd expect the mobile app to eventually get there aswell.
Edit:
Whoops skipped the drawing part, Xournal++ is more for note-taking. Krita is a good choice for drawing.
Krita I don't draw so can't talk about the experience of using it
Krita doesn't have an Android app version though, does it?
Krita (Professionelles Malprogramm) https://f-droid.org/packages/org.krita/
Found this. I think it's pretty new.
https://play.google.com/store/apps/details?id=org.krita&hl=en_US&gl=US
Edit: the app link, not search results.