Specifically “pardo Brazilian”
“Pardo Brazilians represent a diverse range of skin colors and ethnic backgrounds. The other recognized census categories are branco ("white"), preto ("black"), amarelo ("yellow", meaning ethnic East Asians), and indígena ("indigene" or "indigenous person", meaning Amerindians). The term was and is still commonly used, in popular culture and the media, to refer to Brazilians of multi ethnic backgrounds.”
-Wikipedia definition
Starting off with the most obvious the monkey family definitely has some sort of connection to the shandians aka in verse equivalent of indigenous people. It starting with Garp
There’s also a theory that dragons mother and luffy’s grandmother might’ve been from wano. If that’s true that means dragon is probably half shandian and half wanonese
https://www.reddit.com/r/OnePiece/s/0evaTlaGVR
Leaving black and white left which could be from luffy’s unknown mother
Black not really being specific country wise just having African ancestors in general. Seeing as oda made usopp’s nationality “African” I don’t he cares enough to specify sadly lol. Idk what the island or country equivalent of Africa in one piece would be but it’d probably be interesting to say the least if it exists
The most common type of white ancestry being Portuguese. Idk shit about Portugal tbh but maybe they could have an island/country too
Tbh while I wouldn’t mind him giving both ethnicities a special island/people too lowkey I don’t think it’s necessary. It’d be cool tho
Like if his white half is tied to noland somehow and black half idk lmao. I guess the strongest person in history with an Afro or something lol