i don't understand what you mean when you say "a direct experience of our fundamental nature".

you use the terms "knowledge from direct experience" vs "knowledge not from direct experience". i prefer the terms, "intuitive knowledge" vs "intellectual/verbal knowledge".

so a person with intellectual/verbal knowledge of our fundamental nature might say "we are not a mind, we have a mind... self is an illusion... blah blah this flax weighs three pounds". he has read all the books and can recite the koans and even attempt to explain them to people, yet he still struggles to personally internalize and relate with the teachings. i don't think his problem is the lack of an experience, i think his problem is more internal.

when i think of "a direct experience of our fundamental nature", i think of the realization that many people have of "holy shit i'm alive right now". this is not a particularly rare experience. i think the rare and valuable experience is taking something more lasting away from that moment. not remembering it as the time you thought, "holy shit i'm alive right now", but remembering the moment, where you were, what it smelled like.

tldr; i prefer to think of it as "intuitive knowledge" rather than "direct experience". i have no idea what a "direct experience with our fundamental reality" means.

“I don’t know what’s the matter with people: they don’t learn by understanding; they learn by some other way—by rote, or something. Their knowledge is so fragile!”