Maybe you meant L2 instead of integration of another L1? Because I don't see any other L1 other than Bitcoin itself, and by doing self-custody there because of the original nature.
I see some paths progressing towards self-custody in L2 for the mainstream, but they are still far from reaching a trustless state and/or the mainstream.
Since phoenix seems to be making easier/seamless to swap between L1 <> L2, IMO they are a little ahead of the others.