Recently I found Cursa, a Free alternative to Coursera and EdX remote courses with certificates, also Cursa is legal, at least in Brazil.
https://cursa.app/en/search?course=blender
I think OsArch and others with YouTube courses could offer Certificates in Cursa or individually to impulse open-source popularity, specially Blender, FreeCAD, BlenderBim, Sverchok, Inkscape, etc, and recover deserters (users).