The only time I've seen it proposed is on reddit, asking why that didn't happen. There are many reasons it didn't make sense:
- Pre-war, the Jewish population of Germany was much smaller than Palestine, the US, or Eastern Europe
- Post-war, the Jewish population of Europe was mostly not German
- There was no particular area of Germany with a significant share of Jews
- Jews were not exactly welcomed with open arms in Germany, or anywhere in Europe really. It's unlikely Jews would've been happy to remain in Europe long-term
- There was already a large Jewish population in Palestine, with quasi-state organizations. There were some Jewish organizations in Poland pre-war that were quasi-state (there were Jewish political parties), but these were destroyed during the war
- There was no political momentum for a Jewish state in Europe, but there were decades of work towards a Jewish state in Palestine