I have used REX Weather Force and Unreal WX. I’ve tried both. While both of those will inject METAR based weather into the sim, I and many others have mentioned they come with some big limitations. The two most significant ones being that when those mods load weather, it is rendered the same globally. You have no sense of what weather is around you. The second big limitation is the nature of METARS in general. Many stations report clear skies even when there’s cloud coverage so a lot of atmospheric conditions are completely missing when those mods are used.
I found REX to cause noticeable stuttering for me during transitions between different stations. Unreal seemed to work a little smoother but still isn’t ideal. The big advantage those mods have that MSFS doesn’t is being able to look up exactly what the weather will be in game. This is a huge limitation with the built in weather. The info available on the world map is not specific enough to be all that helpful and you can’t access it during flight.
The folks that think it’s possible are MS and Asobo who designed this system. Credit to them for getting the system working half way. Sometimes it takes a bunch of people to figure things out and maybe all the complaints about live weather really boil down to this time/forecast hour discrepancy. How many people who’ve said the weather is not accurate maybe didn’t realize the weather actually was pretty spot on, but just for the wrong forecast hour?