Ask HN: What service/ framework should I learn about next?

Below is what I have become knowledgeable around. What should I learn next as a cloud architect/ app developer? * Spark * Hadoop * Kafka * MongoDB * Graph databases (Neo4j) * Kubernetes * Docker * REST APIs & OpenAPI/ Swagger * Web App frameworks (Django, Laravel, Shiny, Rails) * Machine learning, predictive analytics * Traditional networking, HW, virtualization * Jupyter Notebooks, RStudio * R (tidy), Python (pandas)