As a self-appointed 'mask crusader' I can't express how thrilled I am to hear Hawaiian's new Mask mandate. Aloha and mahalo.
The carrier launched a comprehensive “Keeping You Safe” program for passengers and employees that  requires all travelers  age two and up to wear a Face Mask or covering at the airport and during the flight.

It also banned masks made with mesh or sheer material or equipped with valves, and initiated a new health screening for people who can't wear a Face mask or covering due to a medical condition or disability.  
Hawaiian's  face mask requirement has been in place since May 8. It no longer allows guests wearing mesh or sheer face coverings or valve masks, including exhaust vents of any kind, to board flights following a determination by the U.S. Centers for Disease Control and Prevention that they donʻt effectively block respiratory droplets. A plastic face shield may be worn in addition to a mask, but not in lieu of one.
If you eschew a mask you  won't get on the plane. If you have a medical reason you will have to undergo a personal medical assessment at the airport to be cleared to board​. This means you'll need to arrive at the airport early because the assessment can take an hour.
“We are adjusting and reinforcing our layered safety protocols to ensure we’re providing the highest level of comfort and protection for our employees and guests,” said Jeff Helfrick, VP airport operations at Hawaiian Airlines. “We appreciate everyone’s understanding and cooperation in keeping Hawai‘i a safe destination.”

Pre-board Covid check

Another layer to Hawaiians “Keeping You Safe” program is a check-in process requiring guests to complete a health acknowledgment form indicating they are free of COVID-19 symptoms and will wear a face mask or covering for the entire journey.
Hawaiian is also  disinfecting lobby areas, kiosks, and ticket counters frequently. And using electrostatic aircraft cabin spraying, plexiglass barriers at staffed airport counters, and sanitizer wipe distribution to all guests.

The carrier has been operating a reduced schedule since March due to the pandemic and travel restrictions. It also is continuing continue to cap cabin capacity at 70 percent through September to allow for distancing.

I haven't been on a plane since the pandemic erupted. That's a long time for a travel journalist.  But I am hoping to take Hawaiian to Maui this fall. But only if they remove the 14-day quarantine on arrival regulation. There's no reason to vacation in paradise if you can't leave your hotel or condo for two weeks.

When I do and can fly to Maui  I usually do it in  Hawaiian First Class because of the lie-flat seats. Just so comfy but quite expensive compared to the back of the plane.