After importing GPX with waypoints (XML tag
<wpt>) as overlay they are shown on map and can be also tapped to show information (same way as bookmarks):
Bookmarks can be added to route as waypoint via long tap on it (context menu), the name of the bookmark is copied to waypoint name automatically:
But overlay waypoints can not be added so easy - trying a long tap on them seems just to hit the coordinates:
My suggestion: Add the same context menu (long tap on them) to overlay waypoints as to bookmarks.
Reason: If you have a list of POIs as GPX, which you do not want to add to your bookmarks, it would be much more comfortable to add them to routes (including copying the name). Example in my case: A list of mountain passes exported from OSM via overpass-turbo - even for a small region of italy there are > 300 mountain passes, which I do not want to add to my favorites.
Another example would be using a passknacker export as described in documentation - there are so many passes that it is not useful to import them in favorites.