So the syntax looks to be
repo --name=epel --baseurl=nfs://server:/path
that colon after server is not a spelling error. https://pykickstart.readthedocs.io/en/latest/kickstart-docs.html#id48
That seems to work now. Some error messages made it look like nfs: wasn't supported at all. Thanks.
Well, I spoke too soon - forgot to update the template and the test vm still kickstarted with http repos.
This is not working, the problem persists as described in my original post.