For philosophical Daoism generally, and Zhuangzi particularly, Ziporyn tells us, "the primary idea of a whole is of a correlative pair." (Ironies of Oneness and Difference) One, for all practical purposes, is always two. A psychological experience of oneness is, by virtue of its being experienced, two. This does not negate the possibility of One, something suggested by the experience, but only of the possibility of being One — and knowing it. Or, should we wish to insist on Oneness, then it seems necessary to call it an ironic oneness, where our "not-one is also One". To be human, to be self-conscious, is to be essentially dualistic. Indeed, there seems to be no other foundation for dualism in all the Universe except through life generally, and self-consciousness especially. (Unless one posits a God that creates and especially one who says, "Let us create man in our own image", the Hebrew (elohim) for God in this instance being plural.)
This idea of the whole as a correlative pair is a "single thread" running throughout the Daoist view of pretty much everything. We saw it in the Laozi where the manifest and (somewhat) intelligible world cannot be understood in wholeness without reference to the unintelligible Dao, a coherence (whole) that is necessarily incoherent. Yin/Yang, in Daoism which prioritizes Yin, unintelligibility, is similarly a correlative pair which, if we want to remain true to the human experience, must remain two. Philosophical Daoism is phenomenological in that it does not go where human experience cannot go. There is no doctrinal declaration of Oneness in Daoism.
Ziporyn calls these pairings "asymmetrical" in that they are not co-equals, a common misunderstanding of Yin/Yang; in Daoism, there is a prioritization of the unknowable and mysterious, Yin. (In Confucianism, Yang, the known, is prioritized.)
For Zhuangzi, the essential human experience of self-consciousness in similarly understood as a correlative pair: self and other. "I have lost me" is thus both a recognition of this necessary pairing and the prioritization of one over the other, if we regard the loss of "me" ("I" as object to oneself) as a positive value. But, as we saw in the previous post, this is all very ironic in the sense that the loss of "me" is clearly not the loss of "I", and for Ziqi to observe this phenomenon and explain it would seem to betray it. Thus, we cannot speak of this experience in any absolutist terms; to "have no self" is not to be no-self. It is to be informed by the experience of having no self (just as to be informed by Mystery (incomprehensible metaphysical Dao, Yin) is not to lay claim to having known, realized or merged with Mystery).
Zhuangzi tells us that the hypothetical sages of old realized that their "not-one is also One", and that, as long as we remain human, is about the best we can do.
You can check out Scott's writings on Zhuangzi here.