Understand what you are saying about UL certs. That was a stock fan once upon a time. To my knowledge, nothing like that is available anymore.
Stove fans now days are mostly consumables and disposable.
One really has to be careful these days. Not that such would cause a real hazard, rather if there was ANY code or certification violation near it and almost any problem occurred (even unrelated) your home insurance might be toast. Insurance companies are trying to find ANY way to avoid paying claims.
To move air upstairs from my conditioned family room (downstairs) I have to put in fire dampers in any floor penetration (for ducts) to keep the inspector happy. Strange, I have an open stairwell to the same room ??? The fire damper code was really written for high rise buildings which actually do benefit from fire doors on fire rated stairwells and safety ducting to prevent smoke of fire taking over the entire building fast. Alas, the code is written in the section addressing fire rated walls and floors never seen in a private house but there is no exemption included in single family private dwelling sections. (Reference, National Fire Code).