Nice review, thanks for sharing!

I would pay attention on that, I want to highlight what you probably already point out with "not ideal". It is true that Aurora Store, acting as a proxy, adds more distance to Google, but this does not automatically mean more privacy. In fact it enlarges the attack surface, adding a chain element, and this could lead to security problems, for example if it was targeted with a man-in-the-middle attack.

Probably the sandboxed Google Services/Play Store under a persistent VPN is a better solution. Maybe it helps also clearing their cache routinely to purge any saved data (could this be a nice GrapheneOS feature?).