This discussion was raised last time this story was discussed. I was among its advocates: <https://news.ycombinator.com/item?id=49061890>.
Briefly: no.
Less briefly: <https://news.ycombinator.com/item?id=49060780> and <https://news.ycombinator.com/item?id=49060716> (from the grapheneos HN account directly).
Thanks for sharing - I get the concerns people have raised in those threads, however I still feel something in this space could be useful.
Even a duress PIN which triggers predefined deletion of certain folders, messages and apps could reduce law enforcement exposure significantly.
I think for the case we're talking about here, though, it would be doable. This doesn't need to thwart deep forensic analysis. It just needs to survive a border agent thumbing through the contents of your phone for a bit. If the fake profile data looks plausible, and doesn't raise any flags, the agent gives the phone back and you're on your way.
Hell, I think a setup that doesn't wipe anything, but just drops you into a sanitized, isolated profile for the border agent to look at, would be fine for many users. Certainly you wouldn't want to use this in truly high-stakes situations where it's likely that your device will be confiscated no matter what, and analyzed to death, but for the simple "border agent wants to snoop on my data for a few seconds" case, it's likely sufficient.
(As always, risk analysis can be hard, humans are often bad at it, and not everyone's threat model is the same.)