I think this is a good window for any manager to have taken over. No UCL will be a stipulation for some negotiations but consider the the availability of players in specific positions in the market; abundance of wingers (Dembele, Gakpo, Gnabry, Rapinha) few forward players (Lewa, Richarlison, Nunez, Nkunku).
If Leeds or Everton go down that's more opportunities to assess value. If the club play their cards right United could have a good team to build a foundation from compared to the need of having a multitude of windows to recruit in key positions. Not to mention players who have been unproductive over the years in their last remaining years of contracts thus easier to shift on.
One thing about ETH is that he seems diligent and meticulous. United have in most cases appointed the wrong coaches at the wrong times over the years. I would give exception to LVG who did well in an international tournament beforehand and was the only manager who showed a small percentage of positivity and promise to building something overtime (lots of breakthrough appearances for youth players, United controlled games more compared to Moyes, Ole and Jose).