CAD is certainly the most difficult shortcoming of FOSS.

Freecad is fine fine a single part and it’s actually stable unlike everything else, but doing assemblies requires an add-on. I don’t recall if those work in simulation though. Its workflow also needs more time. It has come a long way in the least several years though. I suspect it will get to be competitive in the next few. Especially as dassault and Autodesk keep trying to inject AI BS and force you further into their cloud services.