At this point, GrapheneOS must introduce a feature to delete only specific data (apps & files) when the decoy password is entered, and then unlock the phone.

They would like to but it's not possible to make a robust feature like that because of low-level architecture of SSDs. Implementing a detectable solution would give people a false sense of security.

https://nitter.net/GrapheneOS/status/2081471477174456340#m