Hi Julie - I'll admit back at my agency, we didn't really do hours by portfolios. And if we did, it was usually just looking at one portfolio to see something in particular. We tended to look at resourcing via teams to see if there was enough work or resources (which the resource planner is great at as you can use the bar chart feature to easily see if your team has too much work a certain week, month, or quarter).
Do you use the Resource Estimate area of the Business Case? If so, maybe there is something we can do with the Budgeted Hours object type.