Given we haven’t bridged quantum with gravity yet, my bet is the function collapses right at the boundary when gravity starts to play a meaningful role.

That’s a more physically plausible interpretation than ever “tick” of the universe actually creates infinitely more universes because every fundamental particle is quantum and each one is constantly interacting under the wave function every plank second. And the infinite number of possible events that a single particle would experience is multiplied by the joint combination of all particles in the entire universe. It doesn’t seem plausible.