Can non-Jewish parents escort their convert child on their son/daughter’s wedding day, considering that they wouldn’t be under the chuppah?
It is permitted for a non-Jewish parent or parents to be under the Chuppah. It is even correct to honor them, as parents who brought up their child, with being present there.
For the escort, the child should be accompanied by a Jewish couple, since this is a halachic part of the Chuppah (see Ramo, Yoreh De’ah 391:3; Iggros Moshe, Yoreh De’ah 3:106), and this can be done by the person’s rabbi and his wife. This should not cause offense if properly explained.