Can Open Source Software Development Or Coursework Count As Work Experience?

No, coursework in classes is part of your education because most coursework is theoretical concepts working in ideal work projects with a teacher to help you out. Unless you created a working project of significant value that is impressive enough to mention, it all falls under “Education”.
Experience comes from a job where many variables exist to cause all sorts of problems and you’ve proven that you can handle not only the work, but that you’ve made things work despite the problems in a production environment.
Believe me, work experience is nothing like class work. The education gives you a foundation to give you skills for a job, but the actual work in a job is a very different scenario in the real world.