Don’t archive or delete the email from the “Google Pixel” account that says “Your Cyber Monday savings have landed,” assuming you got one. Buried towards the bottom, after it runs through deals on Pixel Slate, Nest Hub, and Chromecast is a section that says “Get $10 credit on Google Store.” Yep, a free $10 to spend on stuff.
The code’s terms say you can “receive the $10 discount for purchase of any device,” so that should mean on a Pixel 4 or Pixel 3a if you want. However, I just tried to apply it to both of those and applying the code wipes out the Cyber Monday discount from each. That’s so stupid, Google. Oh, this is likely a US-only thing.
So yeah, best to use on accessories like a Pixel Stand, some USB-C earbuds, or another product not currently on sale.