Gregory's Server
We proposed zeroing memory in firmware when rebooting to fastboot mode to wipe out the whole class of attacks. They implemented this by zeroing memory when booting fastboot mode. USB is only enabled by fastboot mode after zeroing the memory is completed, blocking these attacks.
GrapheneOS already implemented defenses against this attack before we became aware of it. After becoming aware of this attack against Pixels running the stock OS, we improved our existing defenses and added new ones alongside reporting the firmware weaknesses to get those fixed.