What is your suggestion?

As an example, I give the following mod - Emote Craft. Its author has implemented the communication of the mod between clients using a plugin that plays or somehow synchronizes animations between players. This gave more than just communication between clients, because players can see the animations of other players even if they do not have this mod!
I have the opportunity to use a launcher on the project, which itself will install your mod for everyone. However, it does not have the functionality to communicate with the server.
There is a similar mod that has no connection, this is the Figura mod. But we made a bypass using an additional server in the pterodactyl panel, I don’t remember the exact details of the implementation.
Adequate connection with the server from the developer of this plugin is required in order for it to work adequately and please the players.
I am ready to invest a certain amount of money if this functionality is implemented and given the opportunity to play with it on the fabric client on adequate and stable servers with plugins and a good core.

Sorry for the mistakes in the text, I use a translator, as this is not my native language.

With Emotecraft I believe everyone+the server still needs the mod, they just don't need the emote

You don't have to count. I gave an example of a mod that already works 100% in conjunction with a plugin and does not need a mod core. All players see each other, the mod is configured from the client side (and we have a launcher, so we set it up), the animations work even without the mod on the client, the player will still see them due to the plugin. In return, we get stability due to the best core with optimization, the performance of all plugins, a large development space (since plugins and mods work this way), as well as a constantly updated version of minecraft and the server core.

With Emotecraft I believe everyone+the server still needs the mod, they just don't need the emote

??