A GitHub profile on that topic, (semi-) deep knowledge or something comparable helps quite a lot.

At all places I worked, the practical knowledge of the person to be hired was always most important. I don't think it that important if the projects were freelance or just hobby projects. Just having a toy project on Github, that is also hosted somewhere and close to what you would do at the future job can already truly impress people. Combining that with confident self-marketing will make many small startups get very interested.

Once you got some practical professional experience you can still switch to a company that is larger or has more benefits.