More specifically, how can you get access to the Web API FileSystem object on-demand in a way that is cross-browser compatible?

MDN describes two ways to get access: The first by using window.requestFileSystem(). The second with a file system entry object.

The problem with the first approach is that, elsewhere in the MDN documentation, it says that feature has been deprecated. It seems to be only supported on Google Chrome.

The second approach requires having a file system 'entry' object. I would like to be able to create, persist, and alter folders and files on-demand in the FileSystem's virtual drive within the browser sandbox. That means, without the user having just dragged and dropped a file. (As an aside, MDN's article about ways to get access to an 'entry' object link to further detailed articles disclosing that each of them are experimental and to not use them in a production site.)

Is there a cross-browser compatible way to get access to the FileSystem object on-demand? Or is this a technology that has too many bugs to be useful?