You're glossing over an abundance of detail on UL/CSA listing.
I work for a company that manufactures industrial particulate moisture sensors. Due to the location these are commonly installed in, we have been required to jump through a number of hoops (HazLoc classifications, etc) without first being told what hoops we'd have to be jumping through. (Perhaps this is easier at a larger company where there are personnel dedicated to reading the tomes of standards - literally 1000's of pages which cost $$$$). After two go-arounds with UL at ~$10,000 each and no communication other than "Your device does not meet applicable standards" we've shelved the process.
If you've got the inside track for maneuvering, I'd love to hear about it.