I finally have some time on watching some Rune's highlights and analyze his game. I will make some points here:
Things I love from his game: Serve ( and +1 FH shot), Backhand (all forms) and variety (meaning going to the net often, slices and just being unpredictable). All these three things are special shots that will make Rune a special player in the future. Once all three things are clicking at the same time, he is very hard to beat in a match.
The shot that "worries" me just a little bit: His Forehand. I will say this: His FH is not a bad shot per say meaning, he has a lot of variety on that wing. He can use it to get back to neutral during rallies, it is a good defense shot and he can use the FH slice once in a while. However, when Rune wants to be consistently aggressive from that wing, it is hard for him to sustain it. And most of the time, he hits his FH short, so his opponents attack it, just like we saw from Alcaraz the other day. I am curious to see moving forward if his FH "Flaws" are more technical or strategic (mental if you want to describe it like that).
The other parts that naturally will get better when he gets older and more mature: Physical stamina (obviously), Double Faults (as he gets wiser, he will be more wary when to hit big 2nd serves), match awareness and balancing being aggressive/defensive and playing cat and mouse game.
I just want to explain quickly my last other parts point: While it is good that Rune can use his variety at any point of the match, I think he needs to be aware that variety is a great tool use once in a while or as a surprise attack and not use it consistently. Once he starts to realize that, he will be an even better player!