o wait guys zz-porky v2 is neat and all but like
all we need is a way to reduce corner permutation to the set solvable wholly <L,U> and then wholly <R,U> in inspection and we'll have an actual missing link filler
we know that a permutation of 8 corners can be expressed in terms of a key swap + position of BLD sticker. once forcing all the left block pieces into L and U, this key swap + BLD can be converted into a swap of two pieces both on <L,U>. The left block is solved <L,U> so the identity of the pieces that need to be swapped won't change (since permutation fix invariant under <L,U>)
all we need is a way to reduce corner permutation to the set solvable wholly <L,U> and then wholly <R,U> in inspection and we'll have an actual missing link filler
we know that a permutation of 8 corners can be expressed in terms of a key swap + position of BLD sticker. once forcing all the left block pieces into L and U, this key swap + BLD can be converted into a swap of two pieces both on <L,U>. The left block is solved <L,U> so the identity of the pieces that need to be swapped won't change (since permutation fix invariant under <L,U>)