@debaoki.bsky.social had a good thread going on another site about US-based artists who want to break into manga. They don't want to make comics, they want to make manga. They want to be in Shonen Jump. Which is an almost impossible goal to reach. And ABSOLUTELY requires fluency and living in Japan.
It's unfortunate, because there are potentially many great artists who could be producing great comics--here in the US. But because their personal metric of success is "to be published in a manga magazine in Japan" they will most likely never achieve their dreams.