In addition to what Casper said addition of pfzsh would require ARC
approval. Given that the FGAP project intends to do away with the
requirement for modified versions of the shell PSARC may or may not
approve the implementation of pfzsh using the existing method.
Regardless PSARC approval is the next step here if you wish to get this
integrated as a stop gap before FGAP integrates.
However I would say that at this stage adding pfzsh without also adding
pftcsh, and pfbash isn't that useful.
Darren J Moffat