This just sounds like another security nightmare.

We're not in 1980 anymore. Most people need zero, and even power users need at most one or two apps that need that full access to the disk.

In macOS, for example, the sandbox and the file dialog already allow opening any file, bundle or folder on the disk. I haven't really come across any app that does better browsing than this dialog, but if there's any, it should be a special case. Funny enough, WhatsApp on iOS is an app that reimplements the photo browser, as a dark pattern to force users to either give full permission to photos or suffer.

The only time where the OS file dialog becomes limited is when a file is actually "multiple files". Which is 1) solvable by bundles or folders and 2) a symptom of developers not giving a shit about usability.