@scherrey

Is there some way we can add a behavior/interface to some of our Erlang GenServers so it will appear like any other event publisher to our Elixir LiveView app?

Provided they are in the same cluster, they can probably “just” publish messages in the format Phoenix PubSub expects to any pg group (group can be the PubSub adapter name (usually MyApp.PubSub.Adapter) thanks to backwards compitability) which Phoenix PubSub workers joined.

PhxPubSubWorkers = pg:get_members('Elixir.Phoenix.PubSub', _AdapterName = 'Elixir.MyApp.PubSub.Adapter'),
lists:foreach(fun(Pid) ->
    Pid ! {forward_to_local, Topic, Message, _Dispatcher = 'Elixir.Phoenix.PubSub'}
end, PhxPubSubWorkers).

For the Topic it would probably be easiest if the liveviews subscribe to some predefined one. If not, then it’s also possible to get the channels used by the liveview processes and broadcast to them directly.