Well, it doesn't sound like it haha... AFAICT it just wipes it, so I assume you'd get a blank OS when you logged in? Or maybe it wipes it and just doesn't log in.

Actually I just watched this video and it sounds like it actually says "Wrong PIN" before deleting the OS entirely. There's a comment https://www.youtube.com/watch?v=41xbhw8N7NE&lc=UgzwdYjkLuGIb...

could have simply unlocked the device without giving access to anything, and in the meantime, deleted everything. Instead, freezes up in a super obvious way and says it’s loading a different operating system; basically making it obvious that you’re trying to erase all the evidence

A reply said

I've checked their forums, and I'm not really into their arguments against it.

Now I'm curious... the GrapheneOS guy has strong opinions strongly held so I'm surprised he'd agree to half-implement something.