Build a road if it must be permanently greened?

I don't want to break the illusion, but even with robots you need a lawnmower for the edges, the first cut of the season, etc.

That's how the neighbor does it too. First cut. and despite mowing edges, the woman crawls along the mowing edges with the "nail scissors." They don't seem to be able to handle those things.

What does greening mean? Many things die in a strip between 2 garages. Either plant ferns, then it’s not a path, or let it moss over. I would lay down wood chips or gravel there. And then. Let’s see if anyone complains. Do it together with the neighbors: things work much better at 2 meters than at one meter with a fence.

We don't know our neighbor yet (construction has not started yet)

It would definitely be best if we do this together with our neighbor.
2m wide and both install a garden gate in their garden.

I'm only worried about the path to the garden gate

We don't know our neighbor yet (construction hasn't started yet)

I'm only worried about the path to the garden gate

You can worry about that together with the now known neighbor once the houses are built and you have moved in :)

after moving in it is unfortunately too late.

if there is no decent solution we will have to take a door behind the garage additional cost €1500

what can I do now to build a path that must meet the following

it must legally be considered permanently greened (due to development plan)
it must be easy to walk on
you must be able to push bicycles over it
wheelbarrows for garden renovations
all of the above points should also be possible in the rain without sinking into the mud

Have you already asked the municipality or the developer what "dauerhaft begrünt" means? There have already been some tips here, I don't know what other answers you expect. There is no DIN.