The Feds have never approved a Tribal casino that was not located on the Tribe's reservation.
Tribes that have bought property off-Reservation and attempted to conduct gaming operations there have all been shut down by the Feds.
^This is why some Tribes petition and continue to petition the Feds to allow them to expand the borders of their Reservation, in the guise of reclaiming traditional Tribal lands.
The Feds have allowed Tribes to go into partnership with an off-Reservation non-Tribal entity and that non-Tribal entity legally runs the gaming operation in accordance with the State laws of where that gaming operation is located.
The Feds have allowed Tribes to obtained ownership of existing gaming operations that are off-Reservation and run those operations in accordance with the State laws of where that existing gaming operation is located.
FWIW...
For the last two decades I have heard about the Barstow casino project, which is being attempted by the Chemehuevi Indian Tribe and the Los Coyotes Band of Cahuilla and Cupeno Indians.
Other Tribes located within Southern California:
1. Have written the project off as a lost cause and they all agree that both Tribes are simply wasting resources trying to make it come true.
2. Have discovered that the city and other entitles keep promising both the Tribes it will happen as long they keep donating them money.
^Pay X amount to make it happen, oh no new hurdle, now pay Y amount, rinse and repeat for the last 20 years.
3. Have provided support to the Feds to ensure this never happens.
IMO...
This will only happen if one of the Tribes pays off President Biden to direct the Secretary of the Interior to approve it.