Hi there. My situation is almost the same. I am arranging for my wife to return from the Philippines. I was informed by people on the forum (and other places) that the dependant sticker which is placed in the passport does indicate that the holder is regarded as a resident and, as such, will be admitted into Hong Kong. I have booked a quarantine hotel for her from the beginning of September. We are now trying to find a lab in the Davao area which holds the ISO 15189 accreditation. There also has to be a letter from the Philippines DoH or consulate in HK indicating that the labs on the DoH list are authorised to conduct the tests. This is proving difficult as the Philippines consulate say that is nothing to do with them (even though many consulates in HK have done exactly that) and the DoH aren't responding to my emails.
Do I understand correctly that your wife will be coming here in May? That is 8-9 months time. The situation in Hong will most certainly have changed in some respect; good or bad, I do not know. Hopefully it will be better by the time she arrives here.