I am not sure forensic protection is a fair criteria.
Which messengers do have anti-forensics?
Then we can also exclude issues on mobile operating systems, Windows and macOS - because Whonix is Linux based and a mobile version is not in sight at time of writing. (Whonix Mobile Operating System)
Except, perhaps if the mobile client is mandatory is mandatory for sign-up. But then we can already generally recommend against it as per chapter Avoid (Mobile) Phone Verification (Use only with caution).