question

The problem is that Google does not provide a restore-type receipt. That's the system that iTunes provides, to let you request a fresh receipt for all purchases made by the player. We track on all receipt usage and only allow any given receipt to be used once, to prevent players from purchasing something that they then can get over and over again for free (a "replay" attack, basically), or sharing the receipt with others, so that many people can get the item(s) for free. That latter scenario would be very likely to occur for any game with a non-trivial number of players, if we weren't checking whether the receipt was already used.

The best thing to do is to provide the player with a way to get back to their account. Using a secondary login system, like Facebook, Google, or Twitch, means that players will be able to recover their accounts even if they have to replace their device.

But because Google doesn't provide something like the restore receipt, there isn't a secure way to automate replacement of items purchased from a different device. The best thing to do for users who have replaced their device and have no other way to get back to their account would be to make sure your players have a way to contact you, to get help with their accounts.