Multi Desktop & Keeping One App Persistent

I can't count the number of times over the years that I find myself thinking multi desktop would be extremely useful for me, only to be disappointed once I realize there is at least one app (or entire screen) that I always need to have visible.

Opening multiple instances of a particular app isn't always possible, or if it is, isn't always ideal.

If there isn't a way to do this, is there at least an existing feature request somewhere that I can dogpile on?