August updates are live for Google's Pixels — notably behind some Samsung devices. The trend of intermittently skipping those "functional patch notes" continues this month, so we can't tell you what sort of user-facing changes or fixes you might see (if there are any at all), but it does include a good number of "high" and "critical" labeled fixes, so you'll want to pull them down sooner rather than later anyway.
Full security patch notes are available here, supplemented by Pixel-specific changes. Build numbers this month all match, as well, with the Pixel 2 series, Pixel 3 series, Pixel 3a series, and Pixel 4a series all having identical QQ3A.200805.001 builds.
Google still points the inquisitive to look for functional patch notes over on the forum, but this month's post joins other recent months in having none. Though Google continued to include functional patch notes and changes in non-"Feature Drop" releases, maybe the company is changing that practice — though Google's developers may simply be busy recently with the Pixel 4a's software.
The update should be rolling out via the traditional means to supported Pixel devices soon. (It's already available on a Pixel 3a I have on-hand.) But if you're champing at the bit to pull down those sweet, sweet security fixes, you can also manually install them via sideloadable OTA or factory images.