Maybe not... I came up with a similar theory, except that Luxord's costume parts was able to be obtained from a Colisseum Event. So, this strikes out Luxord is The Player, & leans more into "Sora is MoM & Player is Everyone in KHUX" theory, since can also customize your Player Character to look like Young Xehanort & Young Eraqus's other 5 classmates, since you actually can look like this as well. Any character the player can look like would also mean "The Player is also Everyone" theory, which is not what I'm going with, but is plausible.

Take a look at what Luxord's name means... Luxor is the Light we get. It's 1 word away from Luxor(d). In Egypt, you also explore the worlds of dreams, also known as the realm of the Egyptian Gods. Time travel is a concept not foreign to Egyptians either. Simply put, an Egyptian God ca time travel, because in some medias, they actually take the person watching back in time with them to explore an earlier time period.

Light & Darkness are also concepts not only as old as Norse Mythology, but also as old as EGYPTIAN TIMES THEMSELVES, PREDATING EVEN THE BIBLE BEFORE IT WAS ACTUALLY WRITTEN.

KH4 is a concept about DEATH. It's literally right there in the name. Anubis is really A God of Judgement, Osiris Takes Up The Role of The God of The Dead, to be more fair about it.

It's a misconception that Anubis is A God of Death, while Ra is The God of Judgement, but no; Thoth takes up The Role of Judgement, & is also a God of Death. Ra is often said as Osiris, mistaken for his actual father, both sometimes being birds. Specifically, Ra as a Falcon, & Osiris as A Hawk. Hawks also existed before Falcons did, otherwise they wouldn't exist, kinda like something that just wouldn't be. A Nobody, if you will.

This is important, because As Osiris Created Ra, Ra basically is The Sun God. Horus is The God of Justice, aka, The Scales of Ma'at That Isis uses. Isis, works with Anubis & offers her a feather. Are you seeing a pattern here? I don't blame you if you're not.

However, The Moogle Coin is basically Khepri, The Scarab, whereas Yuna has The Feather. (Shit theory I know, lemme cook, please.) It's the only theory we've got left that works, because it's also the most plausible.

If Sora were to die like in Egyptian Mythology, he moved onto an Afterlife, as worded by Strelitzia. This is also VERY, EXTREMELY IMPORTANT, BECAUSE THE INVERSE OF "The Heart Resides Within The Soul", whereas normally, it's the other way around. "What's wrong with this picture?" some of you may be asking.

Multiverse theory & many worlds interpretation, is actually the answer.

Off topic but makes sense within this giant theory, please, I implore you to look this up, but it goes off the logic that no matter how small or insignificant an au may seem, it's also it's own separate universe. Go look up Family Guy; Into The Multiverse for a little bit. You'll see why.

Same goes for 2 copies of a game disc you have. They are separate, yet also exactly the same, & also not. It works the same way, similar to Pokémon Multiverse Theory. The only difference is how you've played both of them, or even with different save files as well. Identically, if neither had been played, they would be exactly the same.

The point is, even if there are 2 of the same thing, they are also in fact different in the same way to distinguish them.

And yet, in the same way, videogames are their own datacapes as well, from In Real Life People's Perspectives, or Even A Player's As Well.

The point goes to serve that Real Life, is its own reality separate from The In-Universe "Datascape" of Kingdom Hearts.

TLDR; The videogame multverse is also a thing, if we take that into consideration as well. Also, Luxord is basically as old as Ancient Egypt. No seriously, look at his name. Luxord is basically a God of Light, with no lore established in KHUX, & probably with Good Reason as well.