My guess is African countries wouldn't want to take in so many black Americans. They'd very scared to. Black Americans (and I'm including any one with a black American mindset, foundational or otherwise) wouldn't put up with the corruption, tribalism and European asskissing, and even though those are good attributes to have it would scare the hell out of the respective African governments and a good number of the people.
They wouldn't grant any citizenship or anything.
Bahamas and some of the Caribbean countries actually have islands for sale. They aren't super huge but you can buy your own island. Even so...white supremacy is global.
Even if some African countries said, yeah, come here and live your best life...with your check. America especially and definitely the former colonial European powers (France, UK), and I'd throw in China, they would find some way overtly and a lot covertly to f*ck with us. No doubt whatsoever.
One thing I know to my core. White people can't live in a world where Blacks and especially more than any, the Blacks that they once enslaved is living well. If we moved to another planet they'd follow us there to f*ck with us. You can't run away from white supremacy, all you can do is fight it with the masses in unity and on code.
White people would lose their sh*t. With blacks losing America they lose sports and entertainment control. And media control as we'd have our own media where ever went. That thought alone would make them try all kinds of gully sh*t. So, I'm not saying don't go, but if its done in enough numbers, it will be a new kind of war with white supremacy.
Hell, we develop our own communities like Chinatown, Little Italies all over the country they'd be targeting it. The check won't end white supremacy, it will do two things. Make them try harder and give those with the check the means to fight it better, especially if operating as a team with on code Blacks.