Updated August 24, 2021
Travelers that are fully vaccinated only have to upload their vaccination cards to travel.hawaii.gov. Those that are not vaccinated can still travel to Hawaii but they must upload a negative PCR test taken within 72 hours of their last flight to Hawaii and must be from a Hawaii approved testing location.
Here is the link to the Hawaii COVID-19 portal website explaining all the details of the requirements: hawaiicovid19.com/travel/.
Vaccination cards must be uploaded to travel.hawaii.gov