Can I upgrade my game by purchasing a better bundle?

It's better to start your own thread rather than hijacking someone else's...however, no, there is no upgrade bundle for that game (far as I can tell)...you would need to purchase the next gen version

Digitally, the Imperial Edition Upgrade looks to be 'bundle only' meaning that it can only be acquired by buying the whole bundle, not the individual upgrade. That doesn't mean that won't change in future, but that's the case right now.

Typically, if its availability would change in future (i.e. becoming a separate, purchasable thing) you're looking at a few months from now. But that's just my opinion based on anecdotal evidence.

For now, though, the Imperial Edition Upgrade is bundle-only, so if you want it you would have to purchase the entire bundle.

Let us know how you get on.

You’re welcome Jack

Thanks for your patience in advance

I hope that you can purchase the upgrade bundle as soon as possible

Sincerely I never experience something like that. All my old purchases exists until now.

Apart from keep contacting Microsoft support I can advise you always save or take a screenshot of your purchased content at the moment and save it to avoid those situations again.

Due to I know that you can purchase Ultimate upgrade to various games, for example I'm subscribed to Game Pass Ultimate, I purchased ultimate bundle upgrade for Forza Horizon 4 and 5 but I don't own base game (I'm using my subscription to play base game)
Probably this is not your case, but it is to show you that proof of purchase is important when base games or specific content is missing from your account

I have purchased the vault edition upgrade and have not recieved ANY of the rewards whatsoever. I have tried restarting the game countless times, and nothing. I have been gameshared the game itself by another account, but purchased the bundle on my personal account. Could this make a difference?

Yes. This makes all the difference. The upgrade wont work unless you personally own the digital version of the game on your account.