However, the Yoga school by itself actually does say that a kind of God exists, as a manifestation of Puruṣa.
For this reason, devotion to God can be part of the process of yoga leading to spiritual emancipation.
Whereas in the Upaniṣads Brahman is everywhere in the universe, in Yoga Puruṣa is the ever-present but aloof Spirit, essentially the same as Brahman.