Comment 1 for bug 1870346

The docs need updating, we do copying netplan through to target, and emit a warning.
Ubuntu Server images have a default policy of not configuring wifi with networkd, but
letting network-manager do that. That said, you can override this policy with a change
to your netplan provided.

I think you can just put, 'renderers: networkd' under the wifis: in your config.

network:
  version: 2
  wifis:
     renderer: networkd
     ....

Note, that we' have an open bug that I'm fixing to allow the 'renderer' key to
not through an error.