Welcome to the forum! 
I had posted a list of resources I use for most CS stuff I learn
For Python, their wiki is indeed a good starting point. Plus, Python is on the easier side too.
For working in Linux/open source, maybe you can see Linux Foundation training courses
Those certifications can be expensive, but if they can land you a good job where you are, they are worth it I’d say.
Security might be a better option though, since there is more demand.
PS. I’m a student 