Urbit has been changing quite a bit. All the OS development has moved to Urbit Foundation ( urbit.org ). Tlon has become a product company that is focusing on a core app just called Tlon ( https://tlon.io ).
There is now competition with a fork of the OS called Plunder. But the urbit OS is also making huge strides in performance with a new Ares runtime ( https://x.com/hastuc_dibtux/status/1765075518637154374?s=46 )
And also there is research moving forward on native urbit. Urbit running on bare metal ( https://x.com/rovnys/status/1766183255097905157?s=46 )