It’s possible, but the theory assumes we’re operating within the same physics, just different scales of time and space. Supposing there are other universes with their own laws of physics is rather arbitrary, and you could literally argue anything :)

I would argue a universe as a unit is a terrible candidate for an atom for a super-universe since our physics assumes it is a closed system. It would be neat if we weren’t bound by the heat-death of the universe and somehow low entropic states could leak back in. But that is all pure speculation and it cannot be proven or disproven from a scientific point of view.