Is Android unit testing on a physical device actually a thing?

Firebase has physical devices for testing: https://firebase.google.com/docs/test-lab/android/available-testing-devices however it's a little expensive. I was wondering if testing things on a physical Android device is a real thing and if there are frameworks for that. I know that there are unit tests that are mocked and run on the computer, but some things like the Android Media Codec Decoder can only be tested on the device