I was hired a while ago, as a front-end developer. For most of the time (around 70-80%), my employer assigns to me work related to Javascript, but targeting native or hybrid applications (Cordova/Phonegap or React-Native) instead of the web. Initially, I expected that it was a temporary need for inherited projects, but apparently, there is no other native developer in the company, and I have to fill that need. In addition, multiple new projects will require native applications, and according to my supervisor, they will be assigned to me.
I am concerned for various reasons, as I don't feel like I have advanced significantly in front-end development over the past months. In addition, it morally feels dishonest on the company's part, as it advertised a different position, and even interviewed loosely related skills.
I am not sure that my worries are reasonable, since maybe it is a reasonably close field and experience has serious overlap (I have failed to see that).
In these native applications, I do not have a backend/API to talk to, nor do I have access to service workers, which I consider crucial knowledge for my future career. A lot of OS intricacies are present, that are abstracted or not necessary when building a PWA or a simple single page application (like the need for native plugins, and knowledge of iOS' and android's build systems for troubleshooting). Finally, debugging even a hybrid app, is different from a website.
Am I justified to think that native development is not aligned enough with PWAs and modern Single Page Applications? Should I be worried that my career is path is decided by someone other than myself?
P.S. I should add that I was asked by my supervisor, if this is something that I'm willing to work on, when he realised that I was hired for a different skillset and lack experience in mobile development. I replied that I welcome the opportunity to learn new stuff, but I don't feel as competent in this field as in front-end.