Pipo if you really want that wipe button feature badly and it fits your threat model (despite it being likely unreliable), I assume you can do 2 things:
- Research how it's done and code it yourself, but it won't be easy as people have mentioned already.
- Ask the person who owns the phone in the image how it was done or which vendor they obtained this phone with an OS that is clearly not GrapheneOS, and repeat what they did.
These are the only ways I can think how you get your request solved. Before you do that, I advice you take some time to rethink or recreate your threat model. On second thought you might not actuallIy want an unreliable wipe button that gives you a false sense of protection...
I came to the conclusion that the GrapheneOS devs apply features in a very serious manner (as in "only if it works consistently" and "no bullshit, snake oil, security/privacy theatre"). Since such a wipe button is not (yet) present in the original GrapheneOS, it's very likely that it's not a trustworthy feature. I'd rather wait for the duress pin and use the anti theft features that are already there and well implemented.