This gets mentioned basically every time the duress feature is mentioned.
Providing the duress PIN is basically always going to be seen as destruction of evidence and, in the US at least, will get the jury instructed that they can essentially assume that the destroyed evidence would have been as bad as possible for you.
On the other hand, refusal to provide a password in the US generally can't be used against you.
Writing your duress password down where an investigation is likely to find it and hoping they use it on their own is a different story however. Then your lawyer gets to argue that law enforcement destroyed potentially exculpatory evidence.
If US law enforcement seizes your GOS phone then just stay silent and trust the encryption on it to do its job. Legally you will be a lot better off.