House directly on the street, no front yard, any experiences?

If you show a bit more, we might also see upcoming problems. Without a plan of the property / land and pictures, it is like fishing in murky waters.

Is there a basement in the property?

Is the house under [Denkmalschutz]?

And there is at least one example here in the forum where the construction contractors unfortunately proved to be not particularly knowledgeable in this matter. Everything that is not standard should always be done with a self-hired architect, not only as a planner but also as a construction manager/supervisor.

Near me, I have seen several cases where the walls of the adjacent houses collapsed. One house even had to be demolished as a result.

So, demolition in such a gap is not easy. I would stay away from it.