Android does allow sideloading but I think there's an argument that competition is harmed due to Google's Play Store having special package-installation permiss

Android does allow sideloading but I think there's an argument that competition is harmed due to Google's Play Store having special package-installation permissions that none of the others can get. This results in competing app stores being required to obtain consent for every single app installation and update while the Play Store can do whatever it likes without any user interaction.