Yeah it would take a ton of work to do all that. Although it does sound vaguely familiar to how I’d wish to expand on Rey’s background in a more canon-centric way. Like your idea, it would need to be clear that Rey’s father (Dathan, I think?) grew disillusioned with the cult on Exegol and escaped on Ochi’s ship from there. But not before stealing none other than Luke Skywalker’s lightsaber from there!
That’s right, one VFX change at the beginning would be to put Luke Skywalker’s floating hand in a medical container just like in the comics.
But Dathan grows weary of the Force in general and pawns off the lightsaber to collectors before settling down on Jakku with a woman he meets there. It makes its way to Maz from there along with the supposed story of how it was acquired (assumed to be an extreme exaggeration). Which would explain why Maz says its “a good story for another time” because she doesn’t even believe it.
No clue how any of this could be communicated through lines though as it’s merely an expansion of stuff present in the movie so no lines could be replaced. But I like the idea that the Skywalker blade calls out to Rey in TFA because it was quite literally rescued from the Sith by her dad.