This is really just my own personal thoughts here. With Viya, I think it is unrealistic to expect a single unified installation document. SAS lists six platform-specific options:

That means you will need at least six unified documents to cover these. However Openshift could be used in both cloud and on-premise installations so I'm sure the list of potential configurations is much higher than six.
Perhaps what would be useful is a Viya installation roadmap that guides you through the various installation options and required / recommended documentation for each.