Basically your best bet is to go to the doctor today and get a covid certificate, buy insurance, and then fly to Hong Kong. I'd say Singapore but they require a 14 day hotel booking. Then fly right back. I'm out of town but this is my plan Monday when I return, assuming it's still feasible.
My non-b requires me to bounce by 5 April but I have commitments the next few days. Ready to transition to a BOI + extension but think going abroad to get the new non-b right now is an even worse idea.
you're eligible for a visa exemption on arrival for 30 days. they have been cracking down a bit though and there's a small chance you could be rejected. if you want to play it a bit safer, get a 6 month multi-entry visa before you go.