I'm amused how people still think that Lukaku's problem is his technique. In reality, his main problem is his movement as he tends to be too static. Technique might be partially his issue but If he doesn't have technique but has world class off ball movement, he would have been great in top club here. Cavani's technique and hold up play in his first season were the same level as Osimhen, but Cavani did well with us in his first season. Imagine Cavani with more pace and less injury prone, Osimhen will be fine. Cavani is also a Serie A striker.
Both Lukaku and Osimhen are two different kind of strikers, Osimhen and Cavani are more similar than Osimhen with Lukaku. Lukaku doesn't like to move a lot, he prefers to stay closed with defenders by bullying them with his strength and power. Osimhen and Cavani like to move a lot and has good work rate, they prefer to create space, lose markers, and run behind defenders.