I've learned the most from shifting levels of abstraction, rather than between programming languages.
When I started at Oracle, on the first day my head near exploded as everyone communicated in ER diagrams instead of pseudo code or more procedural form. Learning to design databases at scale, and learning how far to go in making things metadata driven was hugely educational.
More recently, breaking up legacy application domains into microservices and defining the APIs between them feels to be like a "higher" skill than database design/object modeling.
Probably doing IoT projects would help bring some other skills to the fore.
When I started at Oracle, on the first day my head near exploded as everyone communicated in ER diagrams instead of pseudo code or more procedural form. Learning to design databases at scale, and learning how far to go in making things metadata driven was hugely educational.
More recently, breaking up legacy application domains into microservices and defining the APIs between them feels to be like a "higher" skill than database design/object modeling.
Probably doing IoT projects would help bring some other skills to the fore.