We’ve just started exploring some features related to customizing Discourse for people who only want to see their tracked categories/tags/topics. So we don’t have the option of a custom home page feed yet, but we do have some new features heading towards that direction.
The most useful one for you at the moment would be the ?f=tracked url parameter. So for example, you can visit meta.discourse.org/latest?f=tracked to see only the latest topics from
categories and tags you track.
With this you could add a custom nav item using the Custom top navigation links theme component and use /latest?f=tracked as the URL.