Multi-eternity is already as huge as LT i dont see why there needs to be a "let alone" for him. Iff an omnipotence claim were to be accepted then there is no need for feats at all. No kind of feat can prove omnipotence.
That said omnipotence claims need something extraordinary to be accepted. About half the people in Marvel have been called omnipotent. In the handbooks too. Most of the time omnipotence is used as "really powerful guy" instead of "can do all things".
LT is superior to Multi-Eternity and I was trying to make a point, omnipotence doesn't need feats and those concepts aren't omni, so they need feats.
Marvel multiverse has no such layers. There are infinite universes and new ones are created for each conscious decision. Also multiplying infinity with infinity gives the same infinity.