A lot of the newer local first systems, like Triplit (biased because I work on it), support partial replication so only the requested/queried data is sent and subscribed to on the client.

The other issue of relying on a just the server to build these highly collaborative apps is you can't wait for a roundtrip to the server for each interaction if you want it to feel fast. Sure you can for those rare cases where your user is on a stable Wifi network, on a fast connection, and near their data; however, a lot computing is now on mobile where pings are much much higher than 10ms and on top of that when you have two people collaborating from different regions, someone will be too far away to rely on round trips.

Ultimately, you're going to need a client caching component (at least optimistic mutations) so you can either lean into that or try to create a complicated mess where all of your logic needs to be duplicated in the frontend and backend (potentially in different programming languages!).

The best approach IMO (again biased to what Triplit does) is to have the same query engine on both client and server so the exact query you use to get data from your central server can also be used to resolve from the clients cache.