You can earn points in the US specifically from buying apps or games on the Play Store, subscribing to Google One, making in-app or in-game purchases and subscriptions, and buying books with Google Play, according to Google Play guidelines.
You can also earn points from promotions, which have the ability to increase your earning rate on select purchases.
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If you want a full list of promotions, you can open the Google Play Store app, tap on the profile icon in the upper right-hand side, tap ‘Play Points’, and earn. There you should see a full list of promotions and special offers.
Lastly, if you are at a Silver level or higher, which is determined by how many points you have, you can claim weekly prizes. To do so, just open the Google Play Store app, tap on the profile icon in the upper right-hand side, tap ‘Play Points’, and then ‘Perks’.