You cannot buy books directly inside the iPad Kindle app. You must open the Safari web browser, go to Amazon's website, buy the Kindle book there, and it will automatically appear in your iPad's Kindle app.

Great personalized recommendations and cloud storage for your own uploaded PDFs.

Instant downloads, beautiful interface, and perfect integration with iPadOS. 2. Amazon Kindle

Use Libby (requires a local library card). 🛒 Where and How to Buy eBooks 1. Apple Books (Built-in)

Amazon has the world's largest catalog of digital books, but buying them on an iPad requires a specific workaround due to Apple's in-app purchase fees.

Apple Books, Kindle (via Audible), and Kobo all allow you to buy and listen to audiobooks directly on your tablet.