I'm german so can't answer your question directly. But what worked for me to maintain a career after quitting university to pursue my own startup was to work as

I'm german so can't answer your question directly. But what worked for me to maintain a career after quitting university to pursue my own startup was to work as a subcontractor for larger agencies. You get these types of jobs mostly through your network, have to do some hustling and accepting a low "first project" rate, but if you leave a good enough impression that leaves you as a "safe choice" you'll quickly get projects of ever increasing importance. After a while of this your resume should include big enough projects and brand names that your lack of degree is only a footnote compared to the experience obviously on display.