Yeah, I do hope that an "inter-op" idea can be possible, otherwise anyone who doesn't want to join the duopoly fully will slowly be unable to interact with more and more aspects of commerce, government, etc. I guess the GrapheneOS method of integrating Play Services but keeping the user in control (e.g., being able to block Play apps' internet connections) is something like that, but ultimately it's controlled by Google and there are problems with Play Integrity, meaning some things just don't work.