Fusions of any of the variations you’re thinking of?

Have a look at https://fedidb.org/software, chances are something has popped up there.

my-space style personalised pages

Now that's a blast from the past if I ever heard one. Do people really don't understand why MySpace died? The notion of "personalized pages" went out of style several technological and social generations ago. They're not coming back, and not because it can't be done, because it's an antiquated idea in almost every way.

there’s a good chance you, like many of us, are stuck thinking the internet can only be so many things because that’s all we’ve been given for a while

Given the above it's ironic that you perceive me as stuck in my ways. 🙂

Everything you listed can be done nowadays and there's software for it out there, way too much to list here. Thinking in terms of centralized and/or proprietary platforms is the old way. The new way involves offering services based on open source software, using portable infrastructure solutions, and making a privacy pledge to the users.

Everything you listed can be done either by setting it up yourself or by finding a service that offers it. There's a billion options.