If you want to build each individual piece without licensing from Siemens/Dassault, then yes this would compare to a moonshot.

Parasolid, the CAD kernel owned by Siemens, is more than 30 years old at this point. The same amount of effort has gone into many of the other building blocks as well. OPENCASCADE is a FOSS CAD kernel but doesn't work well for real CAD, and support is hard to come by for companies building on it.

Most startups tend to license these tools instead of building them, but that comes at a large cost that must be pushed down to customers, hence the $$$$ cost of CAD today.