A unified reality in which there are “not two” or there is “nothing apart” surely confirms the illusory nature of separation.
If separation is illusory, then any attempt to not be separate is rooted in a dualistic perspective.
So the basic principle of any guidance which attempts to transform an illusory state of being separate into a state of at-oneness is based on the belief in a divided reality and cannot therefore claim to be non-dual.
However, as long as oneness appears as a seeker with personal needs there will also arise a personal response and guidance from others together with a description of their approach to satisfying those needs.
Teachings apparently happen together with recommendations and processes to help the seeker change or be more open to a better experience.
The open secret perception is that what is ultimately longed for cannot be taught, given, attained or known.
The view here is that the sense of seeming separate is an illusory state which drives the apparent seeker to search for another illusory state called enlightenment.
Any activity which supports this construct is apparently only reinforcing and perpetuating the same dualistic illusion and attempting to create personal experiences that can make the sense of separation more acceptable… for a while.
It is all only oneness playing a game of hide and seek. The open secret exposes what it sees as the myth of separation and personal enlightenment.
It will also attempt to describe the nature of what is and isn’t and point to the paradox of no thing simultaneously appearing to be everything.