When traveling from the USVI to the US there are actually no rules or covid requirements. If you are coming from the BVI then you comply with the USVI entry rules. Once you arrive in the USVI you can stay as long as you like before going home and no additional testing is required. The current rule is a test within 5 days of travel for USVI entry. There is I heard a rumor talk of eliminating that test if your vaccinated but nothing released.