Community/publishing software with relational fields?

Yes, this is a tech-first question.

For a mental hypothesis, I am imagining offering something combining several elements:

• Articles/interviews/etc
• Discussion
• Listings of members' products/organisations (with Follow)
• Listings of external products/organisations (with add-to-your-Stack)

In fact, picture how both IndieHackers and NoCodeFounders
combine some of these elements and relate objects to each other. Variously...

• Members create Startups/products, which are listed as profiles and feed activity for others to follow
• A parallel listing of Tools is provided which members can add to their Stack.

I'm interested in how, with a fair wind and a squint, posts in something like Circle can seem to function as articles as much as forum activity.

But I can't yet imagine how I could extend profile functionality to include other fields, listed and available to follow. Or how to create other objects, not related to users, for users nevertheless to follow.

Without building a platform from scratch in code, how can I come up with such a thing?

Thanks.