Apparently, exporting progress from Google Play Games to iOS Game Center is possible if the game can also connect to Facebook:
- On your Android device (where the game progress is located), log in to Facebook (see screenshot below)
- On your iPhone device, log in to Facebook, and it will retrieve all game information.

how to get goolge play games app on my iphone - Android TV Community
How to install Google play game for ios - Google Play Community
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How do I connect my Google Play account t… - Apple Community
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The main reason I want to do so is because I have many apps from my childhood that have since been deleted from both stores, on my android tablet. But I want the play store specifically because I can download those old apps through the play store’s settings because of Google data that was stored on like the 4 android devices I’ve had in my lifetime. It’s also for convenience sake considering for the past 4 years I mainly use Apple devices and the other android tablet it at least 7 years old by now, so it’s a little dusty. (If you were wondering the apps I’m talking about are specifically Disney crossy roads, a lion guard game, a random Lego freinds subway surfers ripoff, a decently o,d lion simulator game, and a dozen Cartoon Network games.)