So is there any concept of "files" and/or "folders" on the hard drive of these computers? If so, is there a file explorer app to manage them? Or is it black-box

So is there any concept of "files" and/or "folders" on the hard drive of these computers? If so, is there a file explorer app to manage them? Or is it black-boxed, like an iP(hone|ad|od)?