[madeofpalk]

> It's sandboxed storage which lives in your filesystem

It actually barely does. Spec does not require the OPFS to be browsable in the OS's filesystem. I believe all three browsers implement OPFS as a single opaque blob on disk per origin, kind of like a zip archive.

> While browsers typically implement this by persisting the contents of the OPFS to disk somewhere, it is not intended that the contents be easily user-accessible. While the browser might make it seem that there are files, they might be stored in a database or any other data structure. You cannot expect to find the created files matched one-to-one somewhere on the hard disk.

I would guess this makes it much harder to escape the sandbox filesystem if you're not actually in the filesystem in the first place.