Just adding my comment from Gchat, so we won’t lose it.
So I met with other designers and described our issues in the nav. They pushed rather for tertiary nav than overriding PF4 patterns.
So e.g. the host nav would look like this:
Primary > Secondary > Tertiary
Hosts > All hosts
Discovered hosts
Create Host
Content Hosts
Host Collection
Register Host
Provisioning Setup >
Templates >
Compliance >
There are content issues in the nav which we could address in the next release and make it better. (based on next year research in initiatives) Also there were voices for implementing menu search.