Any Pixel really. I’d probably lean toward like a Pixel 8a if you’ve got the budget for it since you’ll get 7 years of updates so you can target the latest Android platform. Plus, Google commonly has sales on the Google Store (definitely avoid paying full price for one). But all the Pixels have good 3rd party ROM support so even the older ones can run the newest versions of Android using Lineage or something similar.

TBH, if you’re just learning, I’d say just use the Android Studio emulator.

A used Google Pixel or Samsung Galaxy should be pretty cheap. Just make sure they support whichever version of Android you want to develop on. Pixel 6's are under $200 USD on eBay currently and should all be upgradable Android 14.

Any cheap tablet really. If you can get devices with different OS versions then all the better as things can change a lot in between versions.

Have you considered trying Flutter first? The components are Material 3 just like Jetpack Compose, but you can run it pretty much anywhere.