I do not think you even need to go that far as modding the controllers. There are adapters that allow older controllers on newer consoles, although an snes to ps1/ps2 adapter might be an odd one to find; additionally you have custom made wireless controllers by companies like 8bitdo, and depending on the frequency used I do not see why one couldn't use an snes shaped controller paired with the same brand's wireless adapter for ps2/ps1. I am going to search for you to see what I can find.
EDIT: this is what you need
https://www.raphnet-tech.com/products/snes2psx_adapter/index.php