Probably not exactly what you had in mind, but there were things like https://www.c64-wiki.com/wiki/SpeedDOS https://www.c64-wiki.com/wiki/SpeedDOS which went

Probably not exactly what you had in mind, but there were things like https://www.c64-wiki.com/wiki/SpeedDOS https://www.c64-wiki.com/wiki/SpeedDOS which went into that direction. Was mostly a hardware modification to make the serial bus parallel, though. But it did extend some commands to handle floppies and their contents, running on both sides.