https://techcrunch.com/2018/07/25/android-ps-final-beta-preview-is-live/

Good news for people who like near-final previews of mobile operating systems. Android just dropped Beta 4 for Android P, marking the last preview milestone before the full version launches. That means the still unnamed OS is just around the corner — promised to arrive at some point later this summer.

As the all of the above implies, this build should be pretty close to final, including all of the systems you’ll see in the shipping version. The release is primarily focused on developers, looking to make sure their apps are up to date with Android P when it ships.