If Orbx/FTX USA CANADA PACIFIC FJORDS, and USA CANADA PACIFIC NORTHWEST are working for you, you probably have FTX: Global already.
If not you can get it here - FTX Global Base Pack
FTX Global Vector improves the looks of coastal areas, as well as rivers, bridges, etc. That may not sound like much, but it makes a tremendous difference in many areas.
You can get it here - FTX Global Vector
This is a shot I made showing how natural the latest update (V1.30) makes beaches look. And this is not one of their enhanced areas! It's actually from Long Island, NY.
As to FTX Global openLC NA Alaska/Canada, just look at the pictures above. They were copied from the Orbx site, obviously. And they're all from Canada & Alaska.
I don't think that it can get a heck of a lot better than that with the computers that most people have now. Ten years from now? I'd like to still be flying sims & try that.
I like what the open LC packages do so much, that I think of them as essential. Excluding cities, towns, and landmarks I think that they look as good as many of the so called "fat" Orbx areas.
"Does it work with REX Plus Overdrive, Orbx downloads, Flight1 Ground Environment X USA Canada Alaska and Flight 1 Ultimate Terrain X Canada"
I've never used either of those (in red), but I don't think that they work with the Orbx/FTX stuff very well.
If you're using GEX & UTX, compare that to the pictures in my second post above.
This is an old post on Avsim (Sept 2013), but it may make more sense to you than me, as I'm only using Orbx/FTX - The truth about FTX Global vs GEX World
But you also have to factor in that Orbx puts out some pretty nice freeware stuff too. True, most of it depends on having the Orbx Global base, but still....
"Do I need it and can it be bought at FSPilotshop"
FSPilotshop does carry some of the Orbx/FTX scenery, but the flightsimstore carries all of it.
Also, If you're over 65 you can get a marker added to your account that gives you a discount on anything that you buy from them. You have to email them a government ID showing your age/DoB. You can cover over any other info that you consider sensitive. I would. Send them an email for more details if interested.
BUT! Before you start buying what I've listed above search your computer for "FTX Central 2".That'll list (and help to update) any Orbx/FTX software that you have.