Please apply for Hong Kong visa at the China embassy in Islamabad, the sponsor from Hong Kong is not mandatory, if you can provide all required documents, it is still possible for you to get a HK visa,
Application for Entry for Visit/Transit in Hong Kong (ID 1003A)

The applicant's recent photograph (affixed on page 1 of the application form ID 1003A)

Photocopy of the applicant's travel document containing personal particulars, date of issue, date of expiry and/or details of any re-entry visa held (if applicable)

Photocopy of proof of the applicant's financial standing, e.g. bank statements, savings accounts passbooks, tax receipts, etc. and proof of employment (if any), e.g. company leave letter, salary slips, etc.

Photocopy of proof of transportation arrangement, e.g. flight itinerary

Photocopy of proof of the proposed leisure visit to Hong Kong, e.g. receipt of joining a package tour to Hong Kong, itinerary, etc. (for leisure visit only)

Photocopy of proof of the proposed visit in the next destination after visiting Hong Kong, itinerary, etc. (for transit only)

Photocopy of proof of the proposed business visit to Hong Kong, e.g. letter issued by the applicant's employing company to confirm his/her proposed business activities in Hong Kong, invitation letter issued by a local company, letter issued by a trade body to confirm the applicant's attendance at trade fairs and exhibitions, etc. (for business visit only)

Photocopy of proof of relationship with the local sponsor (for family visit only)

Photocopy of proof of the proposed visit to Hong Kong (for purposes of visit other than leisure, transit, business or family visit)