The April 2021 security patch is now rolling out to Pixel devices. The update is coming to all phones starting with Pixel 3. Here are the things the update improves, which is listed over at the Pixel help website.
This update also brings improvements for users who were experiencing bootup error. This does not bring updated features but, the next update in June will probably add a few more features to the pixel line.
To check for the update, head over to Settings on your Pixel device and check for software update. You can also wait for the OTA notification or perform your update manually.