The US Virgin Islands are an unincorporated US territory that uses the US dollar, and T-Mobile US is among the operators serving the islands. If your US plan counts the USVI as domestic, you need no eSIM here. Check your carrier's coverage terms first; we would rather you did that than buy a plan you don't need.
If you are visiting from Canada, the UK, Europe or elsewhere, your phone roams here on your operator's international rates. Our plans start at $6.99 for 1 GB over 7 days.