my lukewarm take is that either RTalsorian or CDPR, but in the best case scenario: both, should have official, canon to respective universes, actual play campaigns of Cyberpunk Red and Witcher TRPG
yes this will not be an instant hit like CR or D20, or even VTM series are right now, but it also doesn't have to, get a good storyteller, a few people that are not camera/mic shy, and make them tell a story in a world they already like
i can't speak for cp77 fandom, but there're Witcher fans that also play RPGs and don't know about the witcher system, or if they do, they find it too crunchy, because yeah it's different from D&D 5e! (and I thought the same, but looking under the hood more, so to speak, I think they're actually pretty similar in the amount of fucking math you need to do on a regular)
but it's still a storytelling game, and no better way to show it than thru telling a story
treat it as an advertisement for your rule books, if you have to, make it a podcast with good sound design if not a whole show, and release it on YT, keep talking about it, keep talking about it on official channels, make CDPR talk about it
idk, I just watched the latest ep of NY by Night and it would be so cool to have something like that for Witcher to show my friends, both the ones that are into monster slaying already, and the ones I play other RPGs systems with