RISC-OS also had support for pluggable file systems.
I remember when the first ZIP files started appearing most other machines needed some third party utility to read and write to them (most still do). Someone kindly (bravely) wrote a RISC-OS file system driver for them so the whole OS and any application that needed to access their contents could do so as if they were a regular drive.
Fast forward 30 *years* and Windows Explorer has finally got "native" support for reading/writing ZIP files. (But no other compressed formats.) The lack of innovation in our industry is all rather depressing at times. There are still many cool features of early systems that are missing from today's "advanced" operating systems.