Yes, we can easily get more decentralized that the Fediverse, and we have. Both Secure Scuttlebutt and Urbit are peer-to-peer social networking, with rather different takes on what that means. There might be more, those are the ones I'm aware of.
The decision to make the bottom 32 bits valuable was a clever one, but it's lead to some misunderstanding of how things actually work. Specifically, planets (a 32 bit address) only own an additional 2^32 addresses, called moons. That leaves 2^64 of the address space "wild", these are called comets. There are plenty.
If you want a four-syllable address, they're loss leaders from hosting providers, currently. Two syllables you have to pay for, and one syllable is not usually on the market. A sixteen-syllable address is and will always be free.
How this is handled socially, in a hypothetical future where there are more than 4 billion active Urbit users, is a problem for that future to address.
Moons are the /0 subdomain you get with a /32 aka planet, and comets are the 64 bits of free address space left over in the 128 bits of address width. To create a comet, you make a public-private keypair where the public key hash doesn't collide with owned address space. If you miss, you spin up another keypair and keep going until you get one.
That's really the whole thing. These things need names, as evidence, I present the fact that in IPv4, they have names. To my taste "slash eight" is more obscure than "galaxy", your mileage may vary.
I want for when someones posts an article, to have my local custom filters flag it for interest, schedule it for reading, grab the photos and videos, pull in relevant comments (again filtered, perhaps to my interest graph peers and highly-ranked dissenting opinions), and never have to step foot on the corrupted, ad-ridden, algorithmically boosted web again.
News websites are trash. Reddit and socials are trash. I want complete unfettered control over the inbound stream. Everything first class from engineering principles. The protocol, the data structures, the ranking, the visualization, etc.
I want data I can easily copy into my notebook, easily bookmark, easily remix and respond to.
The web doesn't cut it, and it never has.
P2P social should be article and media centric. Sharing news, blogs, videos, etc. with first class threaded comments built atop it.
Everything is ephemeral and immutable unless you want to save it or publish a correction.