No need to search FT. It's on UA's website lisitng access for GFL's. You would not qualify if arriving long-haul without a UA BP and you would not qualify if departing on domestic any class to HI.
Access policy
The following customers may access the United Global First lounge by showing their United boarding pass for a flight arriving or departing on a same-day (within 24 hours) itinerary.
United Global First customers traveling on long-haul international flights*
Star Alliance™ First customers departing on international flights