Check out BricsCAD. Bricsys recently released shape for free, to compete with Sketchup I guess. It's a reskinned and (greatly) simplified version of their CAD product. https://www.bricsys.com/en-intl/shape/

The higher tier packages have a 3d constraint system. Imagine Sketchup and AutoCAD had a baby with some parametrics thrown in.

I personally own Sketchup, TurboCAD and BricsCAD. BricsCAD is the one I use the most, it obsoletes Sketchup for me totally. I much prefer it to the AutoCAD OEM I use at work and I possibly would pick it over SolidWorks. Although my SolidWorks experience is much more limited.

It's still proprietary but one of the few CAD packages I found that runs on linux and you can own without paying a monthly fee.