As HNLbasedFlyer just posted, I received at least six E-mails from United the weeks and days before my flight from ORD to HNL last month. Here is one of them:
Don’t forget - action required before your flight to Hawaii
One final, required step before your flight in Hawaii:
Go to your Safe Travels account at https://travel.hawaii.gov/#/, upload your negative test result and complete the health questionnaire before boarding. Once completed, you will receive a QR code to present during travel.
All passengers must upload negative test results BEFORE departure. Uploading test results after departure will result in a 10-day quarantine upon arrival.
Passengers connecting through Hawaii are exempt from testing requirements; however, they must complete the Safe Travels application and are subject to the entry requirements of their destination.
Safe travels!