I suspect Starlink modems upload their coordinates. The modem would also need to know its correct GPS location to operate, they mechanically orientate themselves, so faking a GPS signal would not be enough. You would need to modify the firmware.

And even if this was possible, I am sure the Cuban government would not be happy with you providing ISP services at the local dock.

I am sure there are alphabet soup agencies that will get "unlocked" starlinks, but the rest of us will need a local groundstation.