FreeCAD likely helps Autodesk's position - when freecad is so crap, you will likely just pay for autocad/or/other than even looking at alternatives, because you have been already so frustrated.
Having used FreeCAD, I agree.
Constructive solid geometry is hard, but it's all math. User interfaces for 3D CAD are very hard. Open source is terrible at hard user interfaces. Hence, no really good free 3D CAD.
The main competition for Autodesk's Fusion 360 is SolidWorks. It's possible, although not that easy, to get models back and forth.[1]
There's FreeCAD. There are many low end 2D CAD programs. If you're building something bigger than a house or more complicated than a keyboard, though, you probably want a pro product.
[1] https://www.buildercentral.com/solidworks-vs-fusion-360/