Why is the variable not available inside the macro?

I think you’re confusing compile-time and runtime code. For example:

quote do
  Enum.map(unquote(included_handlers), fn {_key, fun} ->
    unquote(fun)()
  end)
end

The quote block is runtime code, so fun isn’t known at compile time, only runtime. And therefore shouldn’t be unquoted.

I think you probably meant to have the enumeration occur at compile time. Something like:

for {_key, fun} <- included_handlers do
  quote do
    unquote(fun)()
  end
end

Thank you! Now that I’ve unquoted the fun value like that, I’m getting undefined function handle_global_update/0 for all Live Views which have it included. Seems like this is happening because it’s trying to compile the call to handle_global_update everywhere it’s used instead of taking the quoted expression before compilation.

handle_global_updates is defined in your EventHandlers module, not the modules using it. You need to either import the function or define the call fully qualified as EventHandlers.handle_global_updates().