The HKSAR passport is an excellent travel document affording visa free privileges to travel to and visit some 150 countries worldwide.
If you are a foreign national permanent resident of Hong Kong you can consider, if you so desire, applying for a HKSAR passport, usually if your present country of origin does not offer you a convenient means to travel, needing visas for most any place that you might like to visit on a regular basis.
In order to do this you must first naturalize as a Chinese citizen and in the process relinquish your current citizenship as Chinese nationality law does not recognize dual nationality.
Broadly speaking, becoming a Chinese citizen means that you have to have some connection to China, possibly via marriage or an ability to speak Chinese, possibly own a business on the Mainland or have property there or in Hong Kong.
The rules are not hard and fast and very many non-ethnic Chinese applicants have been successful in their applications and so it is certainly worthwhile giving it a shot if Hong Kong is very much the only place you can possibly now call home.
There are mechanisms in place such that you do not find yourself stateless, giving up your current nationality before having Chinese nationality confirmed, and the process involves both the Hong Kong Immigration Department nd also the consulate of your current nationality.
Changing nationality is a serious matter and should not be pursued lightly.
However, once your Chinese citizenship is conferred, your ability to secure a HKSAR passport is a right afforded by law and the process of issuing the document is just a simple application exercise.