I'm still not 100% sure why they left. But probably it's just a hard market to compete in. America is iPhone land. I absolutely cannot go iPhone again. It's way to hard ro get your photos off a full phone.
The main reason I want samsung is dex. Being able to plug up a phone to a monitor and get real work done is really nice. Plus their camera might not be the best but it's close.
I can't use custom roms because I need to use Chinese input anyways. And I I need spell check. I did grapheneOS for 2 years after 2 years of lineageOS and I'm done. Way to annoying.