Is it possible to put a 'Collection' within a 'Collection'?
So for example having a homepage with Brochures, Photography, Packaging, etc, and then when you click on brochures for example you go through to a collection of brochures that if clicked on takes you through to a full breakdown of the brochure.
No, it's not possible to nest Collections. Collections are groups of pages. But you may create separate Collections, one each for Brochures, Photography and Packaging. Likewise your pages may contain as much content as desired.
Also Portfolio allows you to create up to 5 websites. Theoretically you could devote one site to Photography and have a second site for print artwork. There are lots of ways to handle this depending on how much content you have.
Does that help?
Nancy O'Shea, Adobe Product User & Community Professional Alt-Web Design & Publishing ~ Web : Print : Graphics : Media
Respectfully, we should expect more from Adobe. Given their vast profits from our subscriptions, Adobe Portfolio should be taken to the next level of customizability. Collections within collections and other elements on a collection page is a reasonable request and a modest effort to implement. From my perspective and understanding of the product, Adobe Portfolio barely crosses the line of being useful for a professional photographer.
Beyond this request, professional photographers need robust tools to interact with clients regarding their client galleries. When cord cutters have a good alternative to Lightroom (if they don't already) then this may be the key functionality that continues to make the subscription worth while.
We don't make the software. We are product users just like you.
Keep in mind that Portfolio is a free perk with your Creative Cloud subscription. It's easy to use & convenient but it's NOT a replacement for more robust web services like Squarespace, Webflow or even WordPress for which you must pay separate fees for hosting, maintenance, etc...
Please submit your Portfolio feature requests below where the actual developers will see them. If your idea is viable and shared by other users, it's quite possible they will add it to a future update.