The Paradox of Oneness can be the same as the paradox of singularity and it can be different. Oneness & singularity can be the same or they can be different, relative to the perspective of Individual choice.
Oneness can be defined as the singularity of all that is realised and all that is not yet realised. It can be defined as both the emptiness of nothing and the fullness of everything.
The paradox is that without the duality of choice, oneness cannot be defined as either nothing or everything; only something undefinable. Something that is the all of everything that has no name and is undefinable is often called God. For this reason Oneness is believed to be a connection with that which is divine.
My perspective is that Oneness with God first requires a separation from God for it to be explored, discovered & experienced. There can be no definitive experience of the Soul without a definite experiencer called the Self.
The paradox of Oneness with the Soul is that there is only one Soul but there is more than one Self exploring, discovering & experiencing itself as being divine or not. The oneness of the Soul with its Self is divine but the separation of its self from the Soul is not. It is only in the twoness or duality of the Soul-Self that the experience of Oneness of the Self with the Soul can be attained.
The Soul is Singularly experiencing its many aspects of Self, including every duality and every distortion of every Singular Self. The Soul is always at One with its Self, even when it’s Self is divided in duality with its Soul.