OpenJSCAD is an opensource software similar to OpenSCAd in many ways, but not compatable. The OpenSCAD user will find it fairy easy to pick up OpenJSCAD.
OpenJSCAD is a CSG style CAD so OpenSCAD users will be quite comfortable with a similar workflow.
You can try out OpenJSCAD by visiting the website: https://openjscad.org/
If you would like to run your own version, hit up github here: https://github.com/jscad/OpenJSCAD.org