So just for my understanding... theyre taking the first three alien films, Predator 1-3, Prometheus and Alien Isolation; wrapping them all into one canon universe?
Among other things (e.g.: everything else you didn't list).
Except they are ignoring AVP & AVP:R.
And likely the rest of the dumb shit.
The authors are choosing to for the purposes of the story they want to tell, that doesn't mean it's "not canon" in the grand scheme of things.
I wonder if the decision to ignore the AvP films was either a personal decision by the writers or mandated by Fox.
I'm very confident it was a personal choice. FOX has been quite supportive of the AvP films in other media very recently.
Scott Allie is more focused on earliest movies, says even all the movies don't really fit in a single neat line.
No disputing that. Absolutely no disputing that.
That's what made it extra hilarious to me when people would complain about "strict continuity" and how the EU "violated" it.
As if the movies were much better.

Hence why I'm a fan of "fuzzy continuity" (and I assume why others like a "multiverse" idea).