> Essentially you need a motorized dish which tracks and counteracts boat movements the entire time it's active.

Not at all true with Starlink, it uses a phased array antenna to aim the beam at the satellite; everything happens in software. What _is_ needed is an accelerometer which can "know" the boat's movement and then adjust its aim based on that. Seems like they're not quite there yet, but there's no reason this can't work.