“Sideloading, a longstanding pillar of Android’s openness, is now being marginalized, placing the Android platform closer to the walled-garden approach of Apple’s iOS.”
Google’s Singapore pilot blocks sideloaded apps that ask for SMS or accessibility permissions. Play Integrity lets developers cripple apps that did not come from the Play Store. The reason given is fraud, and every step routes more installs through Google. The warning comes from a phone vendor selling the alternative, which does not make it wrong.