I searched this quite a bit and not coming up with much so far although I'm hopeful the community can come to the rescue...
I need to be able to customize the look
or
hide access to the HUB... So if users enter the URL to the dashboard it works but the hub will not
I need to control the experience for users external to the company without going down the mashup route. I've seen a lot around the app side of things; using themes, security rules, etc to control the experience but the Hub doesn't have the same level of support.
Qlik Sense Hub is a centralized place for Apps. It is recommended to develop your own web portal and embed the app there if you would like to have a customised Hub.
It appears you want to block the access to Hub page. I believe this can be done on some external network devices, for example web server, firewall
