I'll give you my answer to that one: external validation! ... I am a bit dizzy with the options.
That is fair enough. The options presented need not be-- at the core of the issue-- as numerous or complex as to necessitate 'dizziness." The path boils down to three core concepts that you'll indubitably recognize: suffering, impermanence, no-self. Seeing any of these clearly enough will allow the enlightenment style insights to bubble forth. Further, understanding the relationships between each of those-- such as the relationship between impermanence and no-self-- is also par for the course.
It does not necessarily matter what causes these to be recognized clearly enough for 'liberation' to take place. You may understand no-self simply by reflecting on how you perceive sounds in a causal relationship while watching TV, or you may notice impermanence in a new way while doing formal Vipassana. Technique wise, these communities are presenting people mostly with Vipassana (which focuses primarily on impermanence) and Non-dual approaches (which focuses primarily on no-self). It doesn't matter which one you choose-- other than whether it jibes well with you-- because they're all hitting at the same thing. Said another way: because the 3 characteristics are all interrelated, it does not necessarily matter which one you understand the most of, or why, or when, or how. Though there are some exceptions, I will leave those on the sidelines.
A good approach to all of this is to just read MCTB, read a topical chapter such as no-self, and then highlight what doesn't make sense. Then, sit down with a technique of choice, and try to solve the previously highlighted confusion.
In regard to Enlightenment (and thus ignoring other paths such as Actual Freedom), this is all it will ever boil down to. Everything worth a look/experiment is going to-- in some way-- reference the 3 characteristics. If you see something in your experience, or read something in a book, that talks about them and something does not make sense: experiment until you reconcile the problem (whether to disprove/disregard it [perhaps temporarily], or to confirm it).
[Edit; Addition] And so, the external validation should only be needed insofar as to learn the details of the techniques or to find pointers to said "things that don't make sense." Or to discuss things that don't make sense, or to be steered back on track if you should accidentally falter. Everything else falls squarely on your shoulders. With that said, everything needed for attaining Arahatship is readily available in abundance in MCTB alone, but you may of course find other resources useful. I mention this specifically because, if you have read MCTB, your search for external help need not continue on. Comparing that fact with your personal approach is a good check to see if you are frittering away your time hunting for short-cuts rather than rolling up your sleeves.
Helpful?
Trent