I'm actually similar issues in Frankfurt.

I'm finding that it varies over the course of a single ride. We had a few days where we had slight snow. In the sunlit area all of the snow melted and it's fine. On overpasses and in shaded areas, not all of the snow melted and there is a thin layer of ice under any fresh snow.

When it's actively snowing, it's a nightmare to know where the ice is.

In addition, I live next to the river in the middle of Frankfurt, where almost nothing accumulates and I ride to work which is in the foothills of the local mountain range.

All it seems that I can do is to avoid biking shoes and I lower my seat so I can very easily touch the ground should I start to slip.

Wish me luck!