We've pre-ordered one for the house. They aren't available for portable use yet, and won't be for a while longer.
The technology is quite capable of handling boat- or aircraft-mounted use. It's a phased array antenna that is already doing active tracking of a satellite
moving 25,000 km/h; compensating for the movement of the boat/plane is just a matter of sensing the unit's orientation and doing a co-ordinate frame conversion.
The FCC and other licensing agencies have made it very clear that Starlink devices will not be licensed for mobile use until they've been demonstrated to comply with all the technical rules for fixed-station use during this beta testing phase. Hence, SpaceX added some code to ensure the units will not work
while in motion until it becomes legal
for them to do so. It's a regulatory hurdle, more than a technological one.
The first few blocks of satellites lack the bird-to-bird links for communication beyond the horizon. Those are in the works, along with 2nd- and 3rd-gen user terminals that are less power-hungry.