This is different, by design. Sideloading and alternate app stores are still perfectly fine. It’s just that the developer has to give a bunch of personal into to Google in order for their app not to be rejected by the phone itself. Middleman doesn’t matter which is where most if the regulations are. Problem is that many open source apps don’t have a developer willing to spend the time and money or give up their privacy in order to publish an app they don’t make money on. So it’s designed to kill off FOSS apps.