As far as I know we can only install CIA's to sysnand that were dumped from a 3ds bundled with that game but I'd just like clarification. I saw @cearp's flashcardtimewarp.CIA but I need to read more about that.
You can install anything to sysnand.
However, if you're not using a firmware patch like PBT-CFW or Gateway Mode then the cia will fail authentication and refuse to boot.
Legit CIAs will pass the authentication though.
I've seen a few sites mainly stockholder circlejerk blah blah sites talking about it....but ND Twitter has said nothing and Atari has been as well...I'm wondering if this is a fake story to get Atari stock up