Google released Android ‘P’ Beta 3 (DP4) for the Pixel smartphones earlier this month, now it has released final Beta 4 (DP5) for the phones, before the stable version releases. This has official Android P APIs (API level 28), available since Beta 2. It also comes with July 2018 Android security patch.
If you have already enrolled in the beta program, you will automatically get Android P Beta 2 through over-the-air update. If not, you can download factory and OTA images and flash it manually. Other eligible devices should get the update soon. In the release notes, Google has mentioned known issues related to stability, battery, or performance.
The final stable Android P 9.0 release for the Pixel smartphones is expected sometime in August or September. Name of Android O was revealed in August last year, so we can expect the Android P name reveal next month before the stable update rolls out.