You can easily use an inverter to go from 12v to 110V/240V and just use the stock adapter. Alternatively, you can get your hands dirty and do what I did [1]. However, I'm fairly certain that the non-maritime accounts won't be able to use the service on water (most likely geofenced) so that Starlink can sell their maritime version.

[1]: https://blog.oxplot.com/powering-starlink-on-the-go-with-tes...

EDIT: looks like it's not geofenced based on some other people's comments who've been using the standard terminal on boats.

I think the "rv model" supports 12V. It's not officially supported on moving vessels by SpaceX, but you can find a lot of Youtube videos where people have installed terminals on their boats.