From the list, openscad requires the least tutorial. Solvespace is really easy also, but you need to watch some exciting modelling videos before you get the idea around it. Blender is hard.
OpenScad also gives you a different modelling experience that lets you write reusable models, e.g. if you are a carpenter, 90% of your modelling is sizing and positioning fiberboards to shape a box. You can "automate" such tasks, easily. I wrote a script for myself that does that, and I'm now super fast at modelling furnitures. After some modelling you will be also capable of making such lib. (As a developer, I might be biased)
If you are interested in this library: https://github.com/fxdave/woodworkers-lib
Hopefully, but it's easier to tell each company what they should do instead of giving them rules that they try to workaround. There are many examples.