We have rpk (rom+xml into a zip), but it seems it never got a big following.
Given that it was ripped off from AES in favor of softlist and it's only supported in TI99/4A, I never found the motivation to add it to NES, let alone taking into consideration support for SNES

But if someone decides to revive that, I can help supporting it into NES and SNES. (I'm never against giving more opportunities to users)

The main point is that I consider softlists more powerful, because don't require users to upgrade the xmls inside their own files if we need to add elements necessary to emulation, so I really have no motivation to work directly on this when I have barely the time to keep our lists updated wink