I don’t think Justice League has actually changed any games at all. It’s an exception, and probably one that won’t pay off the way WB hopes, either.

Whatever unfinished scenes got cut from The Rise of Skywalker would likely need fans to do a lot of heavy lifting on the VFX and sound side of things - which is fine (fans have gotten amazingly great at that in the past 20 years) but there’s a huge, huge difference in someone saying “there’s a secret cut they’re not letting you see” and “there’s probably semi-usable odds & ends on the cutting room floor that fans could incorporate into their homemade projects.”

That’s a huge gulf. And as many a fan edit has proven, just because fans CAN edit stuff back into a movie doesn’t mean they should, or that they did it well. Plenty of fan-edits have just as many bad decisions put into them as the original films do.