At the moment there is an discussion about sidewalks at the forum
https://community.openstreetmap.org/t/het-intekenen-van-het-trottoir-als-highway/81169

Both ways of tagging are possible...  but consider that the routing with separate sidewalks is not optimal.
You always have deviations.
Some mappers prefer separate sidewalks for better routing wheelchair users of blind users with dedicated routingapps.
There is no consensus.
eggie
