In this context one super-nice feature of GrapheneOS (do check the legal ramifications though, IANAL) is that it supports a duress PIN. It's an alternative PIN that immediately erases your phone (probably throws away your FDE keys?) and clears your eSIM.

Besides that, it also supports configurable time to reboot after no unlocks. This is relevant because it is typically much harder to exfiltrate data BFU (before first unlock) than after. iPhone also supports this, but only does it after I think 3 or 4 days. On GrapheneOS, this can be set as short as 10 minutes when there is a risk of your phone getting confiscated. Of course, you can also manually reboot, but that's not possible in every situation.