Don't know where to go now

I have a decent knowledge of html, css (also sass and bootstrap), and vanilla javascript. Now, I would like to keep study as a front end developer, but on the other hand I would also like to become a wordpress developer. So, I don't know if i should start studying some javascript framework (which is the missing piece of what most job position as front-end requires from what I can see), or if it is better to start with php (which is required for having a deep understanding of wordpress for what I can see). So is it possible to do, with a javascript framework (I was thinking about staring with vue.js), the same stuff you would do with php regarding wordpress development? Are there any alternative which will allow me to do both things?

Also, on an unrelated note, at which point in time should I study sql?

Sorry if the question may seems confused, but I don't really know anything aside from the stuff I've mentioned in the beginning, thank you for the answer :)