One of the most top-voted threads on Reddit's streamentry subreddit:
[9:07 PM, 8/27/2020] John Tan: Yes pretty much agree with what he said.
[9:40 PM, 8/27/2020] John Tan: But the same insight of anatta must be applied to object, characteristics, cause and effect, production and cessation...which is a more slippery issue. Nevertheless, experientially seeing through self/Self is still most crucial.
John TanFriday, January 23, 2015 at 6:13pm UTC+08
u cannot choose and pick what u like about liberation and enlightenment. Saying one has actualized anatta and uprooted self and attained arahatship is not what u see ppl declaring here and there. I have told u many times what [these people] realized is only at most stream entry. U r talking about liberation and freedom from cyclical existence and therefore u r referring to arahatship.
>the first five looks fairly easy, even somebody trained in Adaita Vendanta could do most of them
Actually what triggers stream entry would be a direct experiential realization of anatman and conditionality. This is different from the realization of atman-brahman in Hinduism or Advaita Vedanta.
Anatman could be summarised as the realization that in truth, always already, in seeing, there is just the seen, no seer, in hearing, there is just sound, no hearer, and so on. Read Bahiya Sutta and Kalaka Sutta for example. Also check out the chapters on selflessness and cessation in this well compiled PDF: https://app.box.com/s/nxby5606lbaei9oudiz6xsyrdasacqph
Also, you should read this well written article explaining what stream entry is, what the realization entails, for example: https://www.reddit.com/r/streamentry/comments/igored/insight_buddhism_a_reconsideration_of_the_meaning/?utm_source=share&utm_medium=ios_app&utm_name=iossmf%20
When the direct realization of anatman manifests and you attain stream entry, you instantly cut off the first three fetters all at once. You will no longer have skeptical doubt about the Buddhadharma because now you have direct experiential realization of it and have ascertained the Buddha's words to be true.
Edit and update on my first point: When you experience impersonality and even nondual even in Advaita Vedanta, it is certainly not the overcoming of self view of the first fetter. There can still be the view of an unchanging self or awareness like vedanta. It is very clear by reading all the suttas that overcoming of self view covers even eternal witness and substantialist nondual views, so impersonality and nondual does not reach the elimination of self view that a stream enterer has attained.
I wrote an article before with citations from Buddha on how all these self views are refuted, including an eternal witness or an unchanging infinite consciousness as self and so on http://www.awakeningtoreality.com/2011/10/anatta-not-self-or-no-self_1.html — stream entry realization covers the dissolution of all these subtle views of self and inherent existence.