Berlin, as far as I know, has a unique history so that it's not always representative of Germany as a whole, in general terms.
That's to say, while Berkeley, CA, has some interesting politics, it does not reflect state or national policies. Meaning, what works in Berkeley (or Berlin) may not be transplantable.
Meaning that while interesting and worthwhile to study as a way to address housing shortages, it may or may not hold a viable answer for other jurisdictions who don't share some of the reasons making this policy viable under particular circumstances.
What's the state of affairs in Hamburg, Essen, Frankfurt, etc.