Insert or update with separated results

I have an API that allows users to update and insert items with a single request. It works by supplying a list of JSON objects to an endpoint that will update items where the primary key exists, and insert new items where the primary key doesn’t exist. I have this working with:

def create_machines(attrs) do
    x =
      attrs
      |> Enum.map(fn x -> get_changeset(x) end)
      |> Enum.map(fn x -> Repo.insert_or_update(x) end)
  end

  defp get_changeset(params) do
    case Repo.get_by(Machine, name: params["name"]) do
      nil ->
        # Insert a new machine
        Machine.changeset(%Machine{}, params)

      machine ->
        # Update the machine data
        Machine.changeset(machine, params)
    end
  end

I get back a list of {ok: Machine} items. What I would like to have though is a list of updated machines and a list of new machines so that the returned JSON is something like

{
  "new": 
    [
      {"name": "machine1", ...}, {...}
    ], 
  "updated": 
    [
      {"name": "machine2", ....}, .{...} 
    ] 
}

I’m just not sure how best to approach generating this result properly. I’ve tried inserting or updating the changeset in the get_changeset function so that I can return something like {:update, machine} and {:create, machine} but then I got stuck with trying to convert

[{:update, machine1}, {:update, machine2}, {:created, machine3}] 

Into the format above for display.
Any advice on what the best approach is for this? thanks