I mean, you shouldn't want to be American in the same way you shouldn't want to be Israeli. Pretty much every single Black radical like Malcolm X reject being American, so I'm not saying anything particularly new. There's that famous speech by a Hawaiian activist titled "We are not Americans." Modern Pan-African orgs and Indigenous communities also reject the label American as well as the settler-colonial borders of the US and Canada. There's plenty of Indigenous tribal nations and communities that have their ancestral lands separated into a US Native American half and a Canadian First Nations half, but they still understand themselves as one people because unlike the two illegitimate settler-colonies, they constitute a real nation.

The only real reason why you don't hear this rhetoric among the various diasporas is because most diaspora communities function as a buffer zone between white settlers at the top and the Black and Indigenous at the bottom. There's a degree of assimilation/gusanofication among the diasporas too, but for the nonwhite diasporas at least, white settlers are too pathologically racist for them to be fully integrated into whiteness and the settler-colonial order. Just like how the US-Canadian border is largely a legal matter among Indigenous nations, whether your nationality is American or Canadian is largely a legal matter among the diasporas.