A novel position however, who is it that knows it is an illusion?

It’s not really that novel. Perhaps it’s expressed in what seem like a novel way.

There is nobody that knows anything. The illusion of self is the foundation of the illusion of knowing.

To observe the point you raise suggests that one must be separate from the illusion to see it as such but will still remain in an illusion.

No. There is no illusion; it doesn’t exist. There is nothing separate from anything else. The illusion of self is the illusion of separation.

How can you objectify the illusion when you remain in the illusion?

There is nobody to objectify anything else. There is no subject and no object. There is no illusion to be “inside” or outside. What seems to be happening is the absolute appearing as what seem to be happening. The self-illusion misperceives that by experiencing a subjective perspective. There is no subjective perspective. There is no experiencing. There is only what seems to be happening, and it is unwitnessed.

(Any notion of subject and/or object would also entail aspects of an illusion)

I don’t really understand what you’re saying. What seems to be happening is the undifferentiated absolute. There is no subject or object. That is the illusion. The illusion of self is subject/object.

It suggests that a non-dualistic realm would also remain an illusion to the observer whether it is experienced as an object or subject or both.

There is no dualistic realm nor a non-dualistic realm. There are no realms. There is only the absolute, which is what seems to be happening.