Klaus Henry would appeal just fine. Pretty much all Arsenal fans (and Arteta according to rumors) would be willing to drop £100m on a lesser version of him in Isak.
It's natural to be skeptical of Gyökeres. He can dominate physically in the Portuguese league in a way that he won't in the Prem (he is not at the level of, say, Haaland, Havertz, Sesko), and he'll have much less space playing for Arsenal. The question is whether his qualities translate to being a striker for a team looking to win the PL and CL.
I disagree that he played well against us Claudius. When you re-watch the comp of his match against us, he looks kind of ordinary. We make plenty of forwards look ordinary of course, and he doesn't have much in the way of teammates, but for me this match hardly quells questions about whether he can continue to be dominant when his physical advantages are neutralized.
Yes, he strikes the ball with real venom, but can he still do so consistently when the game speeds up? Is his pace enough to be an advantage in the Prem? Does he have the guile to dribble past top defenders? How much evidence do we have that he has clever link-up play, or subtle movements to create a yard of space against packed defenses? I don't totally know, but you can't fault Arsenal fans for asking. It is very hard to judge players from inferior leagues.