I guess this is where we eventually get to our own fanedits and personal headcanon, I want to agree it’s probably best to consider TLJ in the standalone category, but a few establishing pieces might need to be added from TFA for it to truly work and make sense to the blind viewer. The ending as ambiguous is fine, ha maybe the ultimate subversion would be that we never did get a definitive conclusion and are left to wonder, definitely a meta take, makes it more fun to me in theory.
It works for TLJ and for TFA as well. We can just imagine what happens after Rey meets Luke.
Thats what i do every day xD