Have you seen the tutorials for FreeCAD by MangoJelly?https://m.youtube.com/channel/UCUWhaOxsRk_5oPPq00_Y7Dw
FreeCAD is the most complete open source CAD project you’ll find. I agree it is a steep learning curve, but it pays off to work through it, if you want to 3D print your designs.
If you want to create 3D models for games, or what not Blender is, as you say a great option.
I donate 25€ per month to Droidian. It uses the Android kernel to run a Debian based Linux distro on phones.
Though I would rather see mainline Linux on phones succeed, I believe this could be the best alternative to iOS / Android (OS) until that happens.