I find it interesting that people here talk about how warez and spyware proliferate on Android, do not know what they are talking about.
I happen to use Android, iOS, MacOS, Linux and Windows. There is nothing inherently compromised on Android. Even with side loading, unless you install something that is nefarious, there are no added risks.
Google will sniff all apps on your phone and tell you if something, even side loaded, has the potential to compromise your phone.
Side loading is a non-issue on Android.
Android is Linux with a skin.
iOS is BSD with a skin.
Both are inherently secure with different layers of permissions for execution and files.
A sideloaded app has no more potential to steal information than any other app on Android because all apps are sandboxed and can't see the cache and data of another app.
Currently add blockers that use a VPN type structure are banned on Android and Apple app stores But I can side load that in my Android and literally block adds where I see fit and add whitelists for apps and sites. If for nothing else, the ability to block adds makes side loading worth it.
I will never buy an iPhone for my own use until I can side load.