How would that work? How will new instances/servers ever get a chance to grow if the fediverse only allowed those who are already whitelisted? Sorry for my limited knowledge about fediverse but it sounds like that goes directly against the base principle of a federated space?
I believe Android apps can be executed more or less natively in Windows now, without the need of an emulator: https://www.windowscentral.com/how-get-started-android-apps-windows-11
If you want an emulator for development I recommend the one built in the Android SDK