Or would it have been possible to be sentenced to slavery as a white person? Or could slavetraders have imported white people as slaves?
More can be said on this question, but you may be interested in these older answers from u/sowser:
Was owning slaves in the US limited solely to black people? Could somebody own white slaves?
How valid is the claim that there were white slaves in the USA post-colonisation?
The short answer is no, there were not white slaves in the U.S.