Related to Pixel 6a’s battery discussion here, I would like to share my recent experience.
I decided to process via Determine if your device qualifies for the Pixel 6a Battery Performance Program (which requires G. sign-in) to find their claim they can't link my IMEI to the G. account I used to purchase my device. The procedure demanded to continue with more info and probably proof of purchase, but I didn't go forward.
Initially, I thought that was because they replaced my defective device in the 1st week, so the IMEI on the device differs from the IMEI on the order.google.com, and honestly, I expected this to reflect the purchase order. Anyway, now my device IMEI is different from the one on order.google.com, and I'll leave it this way. :)
Even more - my friend bought a P6a at the same time I did, also from G. store using the account logged in Play store - the same one used now in Pixel stock OS, never installed GrapheneOS. As expected in that case, the device IMEI matches the order in G. store. Following the same procedure above, G. again said "more information is required" because that IMEI is not connected with the G. account.