Since 6th/7th/8th generation Pixels have moved to the Linux 6.1 LTS branch with Android 15 QPR2 from 5.10 (6th/7th gen) and 5.15 (8th gen), we've closed issues filed about kernel crashes for those devices. Many kernel bugs will be gone and any remaining ones need updated reports.
GrapheneOS adds user-facing system crash reporting to make up for us not having automated crash reporting for privacy reasons. Any hardware lockup or hard reset is called a kernel crash, including holding power, so most aren't useful since they just show a hardware lockup/reset.
We report some forms of system crashes by default including memory corruption detected by hardware memory tagging in both the kernel and userspace. Full reporting can be enabled in Settings > Security & privacy > More security & privacy > Notify about system process crashes.
We don't have it fully enabled by default because we'd get a flood of reports about hardware lockups/resets while devices are asleep and not being used, etc. Rest are near entirely upstream bugs and we can't fix all of them. We focus on the ones detected by our security features.