Julián Álvarez will never play comfortable as attacking midfielder, he is a striker. I'm sure Guardiola won't force him to play as attacking midfielder if Bernardo Silva and Cole Palmer are available in the squad. Unless these players got injured, so Guardiola must have an alternative to change the formation or try to put Alvarez as an attacking midfielder.
He is a striker and does not have good skills to play as an attacking midfielder or even as a forward. He is not like Messi or Dybala who feels more comfortable by playing as a forward, play maker or attacking midfielder.
I agree with you that Guardiola knows about that and he also knows that Julian has yet developed his skills for an attacking midfielder. Maybe he will try to test Julian with different positions than a striker as it is his style. He also requires his players to be able to play at different positions as it gives him and the club more flexibility in tactics.