This may be a bit off the wall and it is only a hypothetical question. If a Jewish man marries a non-Jewish woman and then he dies before they have any children, would she be expected, assuming she was willing, to marry one of his brothers, or agree to chalitzah? I would assume the answer is no in regard to a Levirate marriage as this would create a second intermarriage and the children would not be Jewish. This assumes that the duty to continue the deceased brother's line genetically is not as important as the prohibition against intermarriage. With regard to chalitzah I assume also no, as it only applies to Jews. However, I have no responsas, or halachah to back up my opinions. Any ideas?
"Marriages" between Jews and non-Jews are not considered halachically valid and so there are no issues pertaining to yibum or chalitzah arising in such a situation. A source randomly citing this prohobition: https://ohr.edu/ask_db/ask_main.php/191/Q1/