This seems to work the way I wanted it. Haven’t tried extensively yet but the first route did indeed trigger the “Waypoints only” mode that is possible to manually edit and will do auto-reroute.
Then again, “wanted” is a bit steep. I’ve used the Beeline app for several years and tens of thousands of kilometers and it really sucks. Kurviger is, after a few days, fantastic. For instance, say you want to pass a large city on your route. In Beeline you can choose between fun and fast. Choosing fun lets you go through city streets with red lights, fast means higway for the entire trip. In Kurviger you would obviously add a waypoint on each side and go fast through or around the city and enjoy curvy roads in between. When imprting as mentioned above you will need to do quite a lot of editing but at least it is doable.