The way out is as you've said. To fill the gaps, possibly attempt contributing to an open-source project you feel passionate about, just to demonstrate you can

The way out is as you've said. To fill the gaps, possibly attempt contributing to an open-source project you feel passionate about, just to demonstrate you can collaborate in a team and collectively solve problems. I've done front-end & back-end on web applications, without ever specializing in either. These days, I mostly write single-page applications with a vdom JS library.