Why are you doing so ?
The problem will be still present in all your app that has been downloaded and if no one download your update, you still have this GDPR problem.
I think that you can make invisible your app for all Europe country, so no update now, and after the SDK integration.
Really, I don't know what to do, but something, someone call help us to better understand
Forgive me, but it makes no sense what you said about the "non-updated" apps.
If the user does not update the game, it's not my problem.
I made the necessary changes to be GDPR Compliant and my legal duties are completed.
In my games I'm putting a link to the privacy that the user can read.
From the AdSense (does it include Admob?) console I have selected not to display personalized ads in my games for all European citizens for my "non updated" games.
I do not think a developer can do anything else.
I will never delete or hide my apps from the European stores, also because in reality I do not save any user data, it's Google that saves user data and should think about it to solve the problem, as it did Unity.... and if Unity has solved the problem by itself, I do not understand why it can not even Google...