Ha! I think I solved it. Man this is somewhat involved if you don’t know your ways around and have some understanding of the security features of macOS.
The solution was: Signing the Platypus created app bundle with a self signed Code Signing certificate. 
Here is what I did:
- In the Keychain Access app using the Certificate Assistant, I created a local Code Signing certificate which is trusted only by my computer as it is the CA issuing the certificate
- Created an app bundle via Platypus which contains the Bash script and put it in
/Applications/ - Signed the app bundle like this:
codesign -s 'Restic B2 (test) - Moritz Dietz' '/Applications/Restic B2 - 3.app'
Check the man page forcodesignfor more info
3.1 For good measure I checked that it worked:
codesign --verify --verbose '/Applications/Restic B2 - 3.app'
/Applications/Restic B2 - 3.app: valid on disk
/Applications/Restic B2 - 3.app: satisfies its Designated Requirement
- Removed an earlier entry of the app bundle from the FDA list in the Systems Settings app (they renamed it with macOS Ventura
) - Re-added the new app bundle to the FDA list and switched the toggle to on
Then started the app and here’s a screenshot of it working
