Looks like they are actually enforcing the stay at home order pretty seriously so the 14-day quarantine could be the same. After all, with everyone at home the police don't really have much to do. I'm here on Maui and there is word of people being pulled over and questioned. I suppose if a cop gets behind you and runs your plate he/she can determine pretty quickly if you're heading to/from a store for food or off doing something else.
I read a story this morning that says there are checkpoints in Kauai and that a bunch of people on Oahu were arrested for not leaving parks when told to do so. I've seen a couple police on 4-wheelers here running up and down the beach but they don't seem too interested in chasing people out of the ocean or off the beach, presumably since we're just small groups and not in a public park.