Yup. Considering my Android ROM can reach thousands of various phone models, from 30$ devices to 1000$ deviecs, and I can upgrade devices stuck on 3 years-old Android to latest Android versions, I believe I have a good basis to monetize it.
And so far, I haven't seen any path towards monetization.
Most people won't give you directly money, unless maybe you target very specific niches, like privacy or FLOSS (And I don't believe I can address either of those).
As you mentioned, another possibility is to get revenue through app store (or other revenue sharing sources) possibilites. There is the obvious one, Google Play Store. I simply can't bear Google's bureaucraty, and if I were to try that, I'd have died of old age.
Other actors would be much more willingly to discuss to 3rd parties, maybe Aptoide or Amazon Store would be interested? But then, you can't have Google Services, and usage would be much more limited. Also, I believe that the revenue from people out of Amazon Store is much lower than Play Store, because people have less trust towards it (but I could be wrong there).
5$ per install is imo far from enough, because it barely pays for the bandwidth to download OTAs for one year. Unless you mean 5$ per install and per OTA, but I don't like the idea of having the user pay for security upgrades. Also, it lacks an important property to replace revenue sharing, which is adaptability to users' money (if the user has a lot of money, the revenue sharing will give more money, and it's better for reach to still have a place for low income people, notably indian peoples can give you a lot of advertisement "for free" but they don't have much money)