With so much development happening so quickly with decentralized compute, what comparisons can be made between Nostr, Urbit, and other future projects like Nillion?

I see some overlap, but also key differences.

Between Nostr and Urbit, there is at least the large difference that Urbit is a more generalized decentralized OS, but still mainly just used for social purposes.

Where does the future lead these, where will they compete or converge?