Stop calling it #sideloading when you install an app on #Android that isn’t provided via #GooglePlaystore. It is just installing an app. Not less and not more. The phone is your own device. You bought it, you paid for it. You have all the rights to do with it what ever you want. And to install on it what ever you want from wherever you get it from.
It’s your choice and not the choice of #Google. They only provide the Android system and one option where to get apps for it. That’s it!