"The duress PIN doesn’t give you a second chance and will trigger anywhere you enter it: on the lockscreen, while enabling Developer options, or even while unlocking an app that requests authentication. And unlike a regular factory reset, a duress PIN will erase all encryption keys and your phone’s eSIM partition as well. This makes it impossible for an attacker to access my data just by having physical possession of your device and knowledge of the PIN.

I think the real strength of GrapheneOS’ duress PIN lies in its subtlety. There are no confirmation prompts, no announcements, and no obvious signs that the wipe was intentional on your part. Of course, GrapheneOS is no longer a fringe operating system these days — it has even attracted the ire of law enforcement in some jurisdictions. In other words, a professional attacker might be aware of the existence of a duress PIN. But if you can enter it quickly enough, it achieves its intended effect: no data can be lifted from your phone."

Pretty plainly stated:

Main purpose - delete all data

A nice bonus - the process is semi hidden, no way to confirm mistakes or not

Purpose is NOT - Fool any attacker to think they have your phone even though it's wiped

So it's most definitely doing it's job. You think that job is not enough, fair, but it's living up to it's own stated purposes.

On the Linux box I travel with, my main account is not shown on the list of user accounts when you login. There is a dummy account on the list. When I log into that, it has a full complement of apps and data, and the online email account it connects to is a secondary account I use for travel bookings, random notifications and other throwaway purposes. Financial data, important passwords, personal correspondence, etc, are not on that account. Just the usual stuff a non-computer-savvy guy my age would have: browsing, email and Facebook. If they ever comment on it being Linux, I'll just say "my son set it up for me, I kept having problems with Windows." But so far, the most they've ever done is ask me to show that the laptop can boot up. There's also full-disk encryption so scans won't tell them anything worth knowing.

The passwords I use are high-entropy. There's no duress PIN, though I could set one up if so inclined. So far, I haven't felt the need to.

Lol that's just str8 false in this case, the stated purpose of the duress pin in the article is a system wipe, not plausible deniability.

So whoever has you under duress cannot steal your data

It's not a 'get out of duress free'-card