Here's a comparison on his overall stats compared to Haaland, Kane and Nunez this season. Outside of goals take a look at how he compares to those 3 in terms of passing, shot creating actions, possession and defensive actions.
https://fbref.com/tiny/ulZiX
This is a much more valid perspective than the original question, and one that advances the discussion.
It brings us back however to the centrality of scoring. If he doesn't contribute scoring to a great degree, a striker would need to offer quite a lot in other areas to justify a starting spot on a good team - much more than is normal for a player in his position, and much more than a top striker who does score many goals.
Of the 3 players you're using, his style and statistical profile is most similar to Haaland's. I don't think anyone would argue that Haaland's value isn't heavily tied to his scoring output - if he was the sort of player who put up 7 goals a season, we'd be comparing him to Dominic Solanke (of old). And he would not be starting games for City.
With Nunez, his comparative ineffectiveness in scoring is exactly what makes him a controversial player. That said, his output in many other offensive categories is quite significantly better than Højlund's. Eye-test wise, I think there's also some merit to the view that his constant aggressive runs in behind the back 4 is a strong contribution. Højlund has that element in his game too, but not to the same degree - more usually, it's Garnacho or Rashford doing that for us.
Kane is the one player among these where you'd expect he'd to a large extent justify his reputation even without considering his goal output. But that perception is based on watching him in the PL. The most striking element of your comparison was his unexpectedly weak stats in this regard. I wonder though if that reflects a changed role with Bayern? I tried putting in his last season at Spurs instead, and they do seem to be quite a bit better in many areas.
In any case though, Kane is of course also a player whose goal output is the better part of his reputation. If we want a measure of what it would take for a top team striker to be considered good
without being a very good goalscorer, then we need to look at someone like Gabriel Jesus:
Player Comparison: Rasmus Højlund vs. Erling Haaland vs. Harry Kane vs. Darwin Núñez vs. Gabriel Jesus | FBref.com
In short, I don't see a clear case here that this is a player who'd justify his place without scoring much, through other things he brings. Rather the contrary.
However, he IS now scoring. And already before he did, he was doing a lot of good things that justified a belief that he would be scoring. So everyone's happy here, it's not that.