Due to a policy shift from Google, Barnes & Noble will stop offering users the ability to purchase digital books from inside the company's NOOK app from next week. Google first announced the in-app purchase policy under question in September 2020.
https://www.notebookcheck.net/Buying-eBooks-on-Android-just-became-a-lot-harder-as-Barnes-Noble-stops-selling-eBooks-in-its-Android-app.611385.0.html