I have remapped CTRL+P to Edit.LineUp and CTRL+N to Edit.LineDown and this works in the Intellisense dropdown. For some reason the Intellisense dropdown dims out when pressing CTRL so it gets kind of hard to see the content in the dropdown. It’s not a big problem though, since you can always release CTRL and it will light up again. I mostly use this method when I don’t know the name of the method and want to browse for it.
If I know the name or part of the name it is often quicker to just type some of the letters in the method name. If I know for example that the name of the method I want is GetHashCode then I would just type “geh” or “has” or similar since that would be matched by intellisense.