First of all, thanks for implementing dragging in Outline!
In addition, most Mac programs I’ve used, such as IDEs, allow keyboard shortcuts for Copy, Cut, and Paste to manipulate project files. I keep trying to do it instinctively.
I’ve found a few workarounds (File > Copy To > (navigate hierarchy)) or (File > Duplicate plus dragging). However, in very large or hierarchical projects, keyboard shortcuts plus scrolling and being able to paste is easier than using the mouse for dragging or navigating the project hierarchy within a menu. Plus, it fulfills a common OS pattern. Please consider! Thanks.