You can do this in datomic! I made an end-to-end proof of concept of this using datomic and websockets. The client can open a websocket and subscribe to a query and then the server will react to changes in the database and automatically update the model and therefore the UI (no eventing code required).
Demo vid https://v.usetapes.com/85knuAPruB Longer description in github readme https://github.com/jtmarmon/hackerthreads
I think you have not understood what RxDB is. It is a client side database. It works also when the client is offline. It does not need a stable internet connection over a websocket.
Your example is similar to RethinkDB and others. A websocket streaming json.
A more common solution includes using Datascript[1] as the client side DB and then using something like Posh[2] or Datsync[3] to handle query/pull subscription changes.
[1]: https://github.com/tonsky/datascript