Both mentioned CVEs seem to be about local privilege escalation. So basically yes, if you don't install crap apps, there's a high chance that you are protected. Problem is that it might not seem to be a crap app, but a nice-looking game, etc. Also an attack can come in with an update of any app you have already installed on your phone.
Threat model is probably third party ad and tracking libraries that pay to get into apps. If I caught it, I'd expect it to be from an app to use a parking deck, a colorful desk lamp, an otoscope etc where the developers sold out years ago