Hi, thanks for posting! :) It reminds me of https://togetherjs.com/ which I guess you looked at? What were the shortfalls/differences that you found you had to address? Is your product React-only?
Liveblocks does not come with a specific UI. We're providing APIs to create rooms and share states between users. The state can be volatile (like cursors, focused input, selection) or persisted even when the session is over, like a figma file or a google document (this part is still in private beta). We're using custom CRDTs for the persisted state.
We only have a javascript client and react client, but we plan to support more technologies in the future. Even native clients for desktop or mobile if there is an interest.