It's that time again—Google has dropped the latest Android Pie builds for your Pixel devices. You can get the OTA the old-fashioned way on your phone, but the files are available for direct, immediate download right now.
Google is offering the May 2019 full factory images or OTA files for all three generations of Pixel phones, plus the aging Pixel C tablet (but that's Oreo-based). You can flash the factory images on top of anything as long as your bootloader is unlocked. The OTA files will upgrade your previous stock build, and you don't need an unlocked bootloader.
The monthly security bulletin lists various security patches in the new Android build. The Pixel bulletin reports no Pixel-specific patches, but it's vague on the rest. According to the bulletin, "This quarterly release contains many functional updates and improvements to various parts of the Android platform and supported Pixel devices." Google should have plenty of new things to talk about at I/O this week.