There are some things that you will not be able to account for while editing things within the Blueprint viewport, like how it will look when baked with lighting, or how it will look exactly in the level. That is unless you drag the blueprint into the scene. Then you can continue to edit the blueprint and watch it update in your scene as well.
The functionality within the Blueprint viewport is pretty versatile and flexible. Are you referring to a specific function when you say “normal viewport functionality.”
Regards,