Ruling: Thumbprint scan is like a "blood draw or fingerprint taken at booking."
The legal situation is more complex and nuanced than the headline implies, so the article is worth reading. This adds another ruling to the confusing case history regarding forced biometric unlocking.
Not as part of core GrapheneOS, but an app called "Private Lock" can detect sudden force via accelerometer and disable the fingerprint based unlocking for next unlock.
But yeah, an erase passcode feature with opening a decoy profile would be a great feature to have.
If you do go digging you would get caught. Safest way is removal in those situations. I rather have some data removed which preferably I have backups up. Then have to risk jail time in some country.