Do yourself a favor: Learn on TinkerCAD/Fusion 360 or OnShape. No, they are not open source and both have some REALLY nasty caveats for free users. But both of those are THE most user friendly CAD tools out there and you’ll be able to google anything you need. Learn the fundamentals and the language first.

Once you have that down? FreeCAD is surprisingly not horrible these days and I think I even actually like it. But FreeCAD is still heavily restricted by being “for users, by coders” as it were. So operations that might take one step in every other tool could take three or four because that maps a lot better to the underlying math libraries. And you’ll need to constantly translate between what everyone else calls something and what FreeCAD calls it. www.youtube.com/watch?v=SaTNTUzA5dM is a very good video comparing the two (just watch it at like 1.25x because Deltahedra has a very very very slow speaking cadence…). But they key is that if you know what you are trying to do in the language everyone else speaks, translating that to FreeCAD becomes super easy. Rather than not even knowing how to ask for help in the first place.

OpenSCAD is REALLY nice for building something in a vacuum where you know every dimension you want and have very clean (or nonexistent) interfaces to existing geometry. But, odds are, the vast majority of what you are going to be doing is matching to reference images or even reference parts.