Not only a striker but I think Arsenal needs a star player or an experienced player who can lift the team's mentality to be able to perform optimally, Arsenal's problem in the last 2 seasons is not only with the players but also things outside of that that cannot be controlled so that Arsenal always struggles at the end of the competition as if they cannot play as usual when under pressure.
They already have it, his name is Odegaard.
If Odegaard isn't enough to make Arsenal to lift trophy better to sell or swap him with other players. I think his performance wasn't that good, he's above average, but can't be called as great. So, what's the point to have an above average player if Arsenal have an option to get better player?
Striker is important to be honest, if striker can't score a goal, all the hard work from defenders and midfielders would be wasteful.