Does Hong Kong have notary public?

Yes.

They are however rare in terms of number as being below 400. Many people search for a notary online.

You may find a notary using this website: www.ytt.world. The notary public starts with HKD900.

Yip, Tse & Tang, Notary Public
Hong Kong Notary, Notarial Certificate & Apostille Service
Legalisation by Consulate
Simple notary starts with HKD900
Enquiries Tel/Whatsapp : 6888-9999 (Miss Law)
Address: Wanchai, Lai Chi Kok and Tuen Mun