I decided to just look up some stock Android hardening guides to see what rocks if any I have yet to unturn, and I found these two.
This one by the University of Texas at Austin Information Security Office is a little old (it mentions TextSecure, which is the predecessor to Signal) but it still had some nice tips. Reminded me that I should check my phone’s browser for the same kind of settings I would flip on my desktop.
Then our boy Nate from the New Oil had these two gems and I wish I found them sooner. The second page has detailed places to look for and address, like Connected devices: Connection preferences: Printing: Default Print Service: Use Print Service: Disabled, as he combs through the Settings app.
Securing Mobile: Introduction
Securing Mobile: Settings
If you know of any other similar resources, post them in this topic!