I've been where you are, right about when Zend Framework 2 was becoming hot. I first moved to Hacklang then Java. I reimplemented many of the things I knew from vanilla PHP into those languages, such as a dependency injector, routing, PSR-7, etc. It taught me a lot about strictly and statically typed languages. I then moved to Go and have diversified since. This is a route you can take if you want to move lower in the stack and you like strictness.

If you don't like it, Python is a very reasonable choice as it is very much in demand.