The fast food version of nondual realization says there is no you, nothing you can do, you’re already “it.” Since anyone can quickly realize that for a few seconds, it can be called a fast food version of nonduality.
The Eastern traditional approach, especially Advaita Vedanta, is “slow food” because it says you need to study in a formal and methodical way under a teacher or Sadguru until the intellectual becomes experiential. This takes great effort, study, and investigation, and could take many years. Traditional Advaita at some point confesses the fast food slogan that there’s no you and nothing you can do, but it doesn’t start at that point.
Therefore, you can get the fast food version in the West and experience it momentarily. But can you keep it? Can you value it? The Western approach is hit or miss, it’s the wild west — it’s a disorganized Disneyland of nondual teachers, groups, and institutions.
The Eastern traditional approach is for people who want immersion into an ancient and proven methodical teaching with a single teacher to whom one is committed as a student for a long time, if not a lifetime.
I have no hard evidence, only impressions, and my impression is that the line between the two is fading. I feel that the effect of the Eastern traditional teaching can be experienced by immersion into the fast food culture, into the unrelenting novelty of its forms, and into the good company of self-realized people where you may listen deeply to discussions, ask questions freely, and mingle with seekers, non-seekers, and realizers themselves until nonduality shifts permanently from the background to the foreground of your moment to moment perspective.