As written in the documentation (Prototype interactions and animations) the destination of a Scroll to action can only be an element of the same top-level frame. But with this limitation it is impossible to prototype a common navigation pattern.
On one-pagers there are often floating menu for intrapage links. E.g you have an hamburger icon that opens a menu overlay from where you can scroll to a specific page section. This can’t be realized with an Figma overlay because of the restrictions mentioned above.
There is a workaround, but it seems that it only works because of a bug: You can set the menu overlay as an child of the top-level frame of the one-pager, define the Scroll-to actions and then move the menu outside the frame (as an separate top-level layer) to show it later as an overlay. By doing this all the Scroll-to actions still work, but when you change an action the target will be rested and the navigation is broken.
Maybe you can remove the restrictions that the destination of a Scroll-to action have to be on the same top-level frame for frames that are placed as an overlay.
