Using Opus to Save or Open Files for All Programs

Is it possible for Opus to open or save files for all programs in place of Windows.

No, there is no good way to do that in Windows. What you can do is enhance the standard dialogs to make them do more, e.g. so you can quickly jump to folders which are already open in Opus, or add additional functionality. That's done using separate tools which can talk to Opus.

(And many other threads, but those are two recent ones with some extra info.)