Google details the Pixel 3's custom security chip
 

Google has bragged about its Pixel 3 phones' custom Titan M security chip, but... what is it doing, exactly? The company is happy to explain. It posted a summary explaining the core of what Titan M does, and it's clear the part is at once a watchdog...

https://www.engadget.com/2018/10/17/...-titan-m-chip/