Although a PostgreSQL server is necessary to hold the database for NetBox, it does not have to reside on the same host. The PostgreSQL client is required, but I believe that the need for the server would be better left in the pkg-descr or pkg-message
(In reply to Trix Farrar from comment #0)
Thank you for your suggestion which I appreciate. I have already pondered a bit about to remove the WANT_PGSQL for some while to make the port more flexible.
Thus I will include your suggestion into the next update of net-mgmt/netbox.
NetBox 2.4.8 is already out but I'll wait a few days more because 2.4.9 might be released soon.