I would love a limited maxi-series of like twelve issues or whatever, called something like X-Men: Omega War, where in the distant, distant, DISTANT future, omega mutants who have all found natural ways to transcend/be immortal have evolved into god-like entities who are aligned in various factions and waging wars against each other across the cosmos, and like.....the time-traveling character has to find some way to avert the war and save the future by figuring out how to keep the present-day omegas from ever losing sight of their essential humanity to the degree where they start operating just on a cosmic/big picture scale that doesn't factor in the needs of singular, individual lives.
Like, that way you can have Feat-apalooza for all omegas, you keep it essentially AU in all practical ways that matter, so like, the feats are THERE but they have the context of 'will take hundreds or thousands of years of learning about their powers to be replicating this stuff so that's why it doesn't impact current comics', there's not directly the whole 'oh they are to blame for doing this or that thousands of years in the future' because AU time travel rules means that it wasn't actually them and you can't exactly be blaming them for shit they haven't done yet and now will never do, etc.
Easiest way I can see to have our cake and eat it too, with various characters, and give glimpses/pay homage to what the comics keep saying omega mutants SHOULD be capable of, when they'll never actually allow them to operate at that level in current-set comics because it would break the stakes and mean they're essentially solo-ing anything less than cosmic entity level antagonists.
(But also, make it a self-contained side comic that doesn't impact the rest of the line and take over everything a la Sins of Sinister or Judgment Day, since that shit IS annoying and like, completely unnecessary for something like this, which can easily be a self-contained storyline that's followed and resolved in just one single temporary series).