Hi, well you can do both.
There is a Chamfer OP in path that will generate a path based on an edge and for which the toolpath is offset according to calculations for a chamfer tool bit (a simple D bit can do the trick if you're a hobbyist with the tools to make it).
Alternatively you can use one of the 3D Surface OPs, (dropcutter or water line). To activate then you need to:
1. Enable Experimental Features (the procedure to do so is explaine in the FreeCAD wiki page of the same name.
2. Go to Edit, Preferences, Path, and in the third tab activate OCL based features.
Once you've done that and restarted FreeCAD, the 3D surface OPs will be available as a drop-down menu of 3D Pocket. (i would not rely on 3D pocket for the task, but maybe someone will have a better offer).