Hey,
It's totally dependent on your interests as to which domain you will have to choose for your career prospects.
Since you are well versed with python programming learning automation tools like selenium with python would be a lot easier. Automation is one of the thriving fields and there's a demand for skilled people who have a thorough knowledge of automation.
Since you already know Linux from an administrator perspective along with scripting skills acquiring automation skills would definitely go a long way in opening up career prospects for you.