Google Pixel 3's Titan M security chip gets explained in blog post
3

Google Pixel 3 XL
Essentially, this new piece of silicon is in charge of keeping the Pixel 3 smartphones totally secure, with the chip itself being tied directly to the operating system’s secure boot process. This allows it to save the latest safe version of Android, thus preventing attackers from rolling back the firmware to an insecure version. Moreover, Titan M can also block attempts to unlock the bootloader. Aside from these more technical tasks, the security chip also limits the number of sign-in attempts and manually verifies the lock screen unlock code.
Looking at Titan M as a whole, the chip is independent and also uses a protected flash memory, two details that make it much harder to hack. Because of this, Google is also using the chip to secure authorized payments with apps that use Google’s StrongBox KeyStore framework. Furthermore, the Google Pay team is hoping to introduce support for the chip in a future update.
In light of the recent privacy controversies that have surrounded the tech industry, it’s certainly no surprise to see Google focus so heavily on its chip. Moving forward, the chip will likely become a central part of Google’s future Pixel devices, not just the Pixel 3 series.
source: Google
Things that are NOT allowed: