My understanding is that the lithium itself isn't the issue, it's that lithium batteries require other rare earths like cobalt where as sodium itself is not only more common than lithium, but it uses more common material like iron or tin in its battery chemistry that are also less problematic.

That's good to hear. I'm hoping freeCAD has a Renaissance similar to blender did the last few years that makes it competitive with the popular closed source tools, but it sounds like it's getting there.

Did you find a good alternative to fusion?

Honestly the popular linux distros are pretty polished / user friendly these days. You'll run into little issues, and you need to be at least a little bit curious / tech savvy to figure them out, but it's nothing a little googling can't solve typically.