I’m not personally a fan of duress codes that wipe data as a security measure for that threat. In some jurisdictions that would be considered evidence tampering and may cause you more grief. In the “rubber hose” threat model it would just cause you a different type of grief.
So I personally won’t be pushing for that kind of spycraft for the L5, but of course you are free to develop it yourself if you want it. Instead, I favor what I’ve described as “user personas” in this article as well as in a few places here in the forum whenever travel spycraft on the Librem 5 comes up.
To summarize, I think the safest approach is one that allows you fully comply with customs/border agents or other officials, and not one that requires you to lie (you are not as good a liar as they are lie detectors), conceal, or smuggle something. So with user personas, before you travel you backup your home persona, and replace it with your “travel persona” or “border persona” that only has the data, accounts, and information you need while traveling. Then if someone compels you to turn over your phone, you can comply without putting anything at risk. Then when you get home (or get through a border checkpoint, or whatever the situation is) you can potentially (depending on your threat) restore a different persona from local or remote storage.