What is exactly Google Play System Update buried deep in the settings that can be manually updated and usually has a date of say, eg, May 1. Is it part of Project Treble from Google to decouple parts of OS from full system upgrades and make more Modular updates possible?
To keep it super simple, think of a Google Play system update as halfway between an OS update and an app update. It’s a system service update if you will.
It contains more modular parts of the operating system that can be updated without specific knowledge of your exact device hardware. It’s an approach Google uses to push bug fixes and feature updates to you faster than your vendor and even if your vendor no longer supports your device.