Maybe I am missing something, but Zikr sounds suspiciously like japa (https://en.wikipedia.org/wiki/Japa), which is a well accepted form of concentration meditation in all Dharmic traditions. Many teachers will ask neophytes to have a regular japa practice, where you recite a mantra a certain number of times often with the help of a mAlA, first audibly, and gradually, mentally (https://en.wikipedia.org/wiki/Japa#Degrees_of_loudness). The idea being that it's easier to focus on a gross object at first to keep your mind steady, and later proceed to more subtle forms. Patanjali himself recommends that Om be chanted and its meaning reflected upon (https://www.himalayanacademy.com/saivite-scriptures/patanjal...).
The forms of meditations in dharmic traditions is quite bewildering. Patanjali himself recommends to concentrate on anything that you are comfortable with (https://www.himalayanacademy.com/saivite-scriptures/patanjal...).