"And I know for a fact that bicycle navigation is possible, allowed, not forbidden."

Do you also know whether car traffic is allowed?

I don't think highway=road is a good idea. It was highway=pedestrian and will be highway=unclassified (or highway=residential). So one of these would be best.

We could leave the highway=pedestrian and add bicycle=yes until it's clear whether motor vehicles can use it, or we could change to highway=unclassified and add the suggested fixme about access.