Is this usable in addons? If I were to use to create files, can then the user locate those said files (same name) and modify them?
This is usable, however if you dig deeply Firefox only supports parts of the API. What this leads to is essentially what’s described at
Does that mean this is not implemented?
Although in the bottom, it shows as implemented since firefox 50?
For all I know it is implemented, for “a filesystem”, which to my understanding isn’t a normal physical filesystem here.