The only open-source CAD option I've seen that might be suitable for doing this kind of design work is FreeCAD, or its Ondsel fork. There are not many people available to FRC teams to teach them how to use these programs, and there's a high risk of them running into serious bugs or limitations.
Most FRC teams use professional CAD packages (like Autodesk Inventor and Dassault SolidWorks). These packages are offered to teams for free. Many teams have mentors with professional experience using one of these programs. OnShape has taken over in the last couple of years as the most popular, because it is easier to license, doesn't require installation permissions, works on any device with a web browser, has an easy to understand and administer way for multiple people to collaborate on a model, and has a critical mass of community scripts, part collections, and tutorials.