Is there a way to give a user limited, non-admin account access in cPanel?

I have a dedicated virtual server with two domains domainA/domainB on it. Each domain has its own cPanel account. I want to give someone access to very specific items ("metrics" items, ie: Webalizer, AWStats, etc) on each cPanel.

The user already has a standard email/FTP account on one of the two domains. But I can't find a way to assign that user access to additional features.

In WHM I can “Add A New Account” - create the username, add the “Feature List” and then select domainA and I get an error saying domainA is already assigned to an account. This makes me think this is creating "Admins" for new domains...But not how to add a limited user to an existing domain.

Is there some magic that I am missing here?

Unfortunately cPanel does not support sub-accounts, or other permission management in the way you're looking for. Every cPanel account has just one login, which grants full access to the account.

The feature request you linked to is real, and unfortunately it does appear to be shelved.