Is there some coagulated astrophysical theory about reality being black holes all the way down? I.e. our universe being a region of spacetime isolated inside a

Is there some coagulated astrophysical theory about reality being black holes all the way down? I.e. our universe being a region of spacetime isolated inside a black hole, each black hole inside our universe also hosting one, the expansion of the universe possibly being the black hole growing, etc?