Oh and I didn’t answer your original question: If you have to select between Ruby and JavaScript, 100% go with the JavaScript course :)
Though DevOps and “free” or “open source” doesn’t really mix. The moment you touch DevOps you’ll either land at Amazon (AWS) or Azure (Microsoft) or Google (Google Cloud).
Sure, in theory you could set up your own servers with your own clusters, but then you’re a system administrator and not DevOps.
Btw. Azure might be Microsoft, but they have plenty of Linux options on there, it’s not a Windows shop at all.