What about having high standards on tests and some kind of practical evaluation, but not requiring third-party credentials to enroll, particularly at the gradua

What about having high standards on tests and some kind of practical evaluation, but not requiring third-party credentials to enroll, particularly at the graduate/professional level? i.e. not going for the 18 year old undergraduate market, which is very competitive, but something more unique. (My German is 1- to 1 right now, but I could probably get to 2- to 2 without too much work over a year, but I have no undergraduate degree. If I wanted a professional degree without completing undergraduate, I'm mostly stuck with UK schools (LBS, LSE, ICL being the top options) in MBA or Econ, or a back-door "special student" PhD route somewhere. If there were a German institution which made this straightforward, it would be worthwhile for a lot of people in the mid-career stage in technical fields who don't have formal credentials. Those people would be far more likely to remain in Germany, or at least to maintain some connection to Germany.)