I was always worried about situation like this. Wiping out the whole device is easy to prove.

When I was designing my secure vault app for iOS[0], my approach was to make one of the “folders” (I call them vaults), to trigger the wipe out without any sign of doing so while retaining the data in the opened vault. It technically only deletes the index and the keys, and obfuscates them by replacing them with random bytes.

I already heard from a person that was forced to open their app but was let go, because they complied.

[0] https://vaultaire.app/