Senior Data Engineer-Which Tech stack to upskill?

I am a senior Data engineer(9YOE) and have worked on a large scale Data warehousing, Spark, Orchestration(Airflow) and visualization on AWS and Azure. I currently don't have scope for tech stack improvement in my current org and would like to learn and implement my personal projects. So far, I have been advised to learn golang and kubernetes so that I could deploy ML models in the future or even move into observability space. Any suggestions on what tech stack I should learn? I want to jump to startups in a couple of months and eventually move into a pure software engineering role. Already working on leetcode and practicing system design for the same.