I agree that Milan's main target should be to buy a much more reliable striker from now on. Giroud and Origi can't show the expected the level of performance. Giroud makes some contribution with goals but the number of them isn't so many. Origi was transferred with nice hopes but he was much worse than Giroud. I don't remember Origi scoring more than a couple of goals.
If Milan increase the productivity of their attacking line then they can be much more competitive for the Serie A title again. I know Leao is doing great also by scoring so many goals despite not being a striker. But this isn't enough. Milan would make use of a striker who can be even in top scorer rivalry.
Leao, by the way, is positioned as a striker, and I think that this is a very promising player who has yet to reveal himself. And Leao is Milan's top goalscorer this season with 15 goals, Giroud finished this season with 13 goals in Serie A. But Giroud is not young and will need a replacement soon, so strengthening the attack would be worth considering.
Also, Milan don't have the strongest mid line, so they have some work to do, but I don't see any significant activity in the transfer market yet.