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Android won't kill sideloading after all, but new verification rules will make it harder
(www.techspot.com)
This is a most excellent place for technology news and articles.
Okay, but Google uses it in a way where directly going to the server they host F-Droid.apk, downloading and installing it counts as sideloading.
If anything, using Google Play is sideloading by that definition, since I can't just download a release from the originators' server, they need to first transfer it into a secondary location, Google's servers, and I can only install it from there.