I wouldn't be surprised if some (or most) browsers don't implement the parts of the FileSystem API that are designed to access the users home directory (with pe

I wouldn't be surprised if some (or most) browsers don't implement the parts of the FileSystem API that are designed to access the users home directory (with permission). But the parts that are for a "sandboxed virtual drive" will be, that is what's needed for web apps and PWAs for saving their own data in a local block level storage (rather that IndexedDB or LocalStorage). That part of the api is very much designed for enabling things like WASM Sqlite. https://developer.mozilla.org/en-US/docs/Web/API/FileSystem https://developer.mozilla.org/en-US/docs/Web/API/FileSystem "This interface will not grant you access to the users filesystem. Instead you will have a "virtual drive" within the browser sandbox."