Yes I’m power scaling, fuck you.
If Viltrumites (from invincible) invaded the OPM universe, how much effort would Saitama have to put in to defeat them? Each and every one of them basically scales the entire universe, so I can’t imagine he’ll be able to one shot all of them, but would they give him the fight he’s looking for?
Id say oneshotting all of them is just a question of how much collateral damage is acceptable.