@BlueRibbon - You probably won't get pulled over and it's ok to have everyone in the same car. As soon as you leave the car you'll have to break up into two groups, though. Two separate groups at the beach 6' apart, two groups as you walk down the sidewalk, etc. The US surgeon general got a citation for being in a park that was closed due to covid so I'm not kidding when I say enforcement is strict.
The no-groups-larger-than-5 rule must seem so stupid to visitors, but there's actually some logic behind it. Lots of people in Hawaii live in multi-generational homes or "monster" homes (single family residences that are broken up into 3-6 individual dwelling units). It's not unusual for one "household" address to contain 20+ family members. And if you see 20 people gathering at the beach, you can't tell if it's a large family or a party.