Handle barriers like potentially closed roads?

[rumbrummer]

@Patrick

Even some that use OSM data?

Yes - e.g. Calmoto does. If you plan the route mentioned in Route über unbefestigte Strasse - #2 by rumbrummer, the route is planned through the barrier (without any notification):

https://calimoto.com/calimotour/keilberg-r-5aDaIpqoJR