Have a look at the node network in Barnim county north of Berlin. It works fairly well with my preferred rendering and routing tools (waymarkedtrails, mapy.cz).

Example:
https://www.openstreetmap.org/relation/8946367

I certainly agree with Streckenkundler’s proposition not to introduce a solution that interferes with established tagging, but rather add a tagging for node networks “on top”.