Just dual boot…
They’re both really good (considerably better at what they do than FreeCAD is, to be honest), but they don’t do what FreeCAD does. Blender is for art, so that’s a different thing entirely. OpenSCAD does mechanical part design, but it only does mechanical part design. FreeCAD can do architectural CAD, BIM (Building Information Modeling), civil engineering stuff (e.g. working with survey data/site elevation), FEA (Finite Element Analysis), 2D drafting, stuff with NURBS and point clouds, texturing/lighting/rendering, CAM and CNC (i.e. toolpaths for a mill or 3D printer), etc.
I have actual designed 3d print stuff in Blender and it turned out fine. There are people out there who only use Blender for 3d modeling and there are even plug ins that allow better functionality. Though, I’ve been trying to transition to Freecad since it’s much more cad focused.