Phoenix.Logger defines an install/0 function to attach telemetry handlers:

  @doc false
  def install do
    handlers = %{
      [:phoenix, :endpoint, :start] => &phoenix_endpoint_start/4,
      [:phoenix, :endpoint, :stop] => &phoenix_endpoint_stop/4,
      [:phoenix, :router_dispatch, :start] => &phoenix_router_dispatch_start/4,
      # [:phoenix, :router_dispatch, :stop] => &phoenix_router_dispatch_stop/4,
      [:phoenix, :error_rendered] => &phoenix_error_rendered/4,
      [:phoenix, :socket_connected] => &phoenix_socket_connected/4,
      [:phoenix, :channel_joined] => &phoenix_channel_joined/4,
      [:phoenix, :channel_handled_in] => &phoenix_channel_handled_in/4
    }

    for {key, fun} <- handlers do
      :telemetry.attach({__MODULE__, key}, key, fun, :ok)
    end
  end

Is it somehow possible to replace these with custom handlers?