The good thing Chelsea did is signing Delap cause if they were hoping on going into next season with Jackson then they would've suffered more than last season. Delap might not be a super striker but he's Premier League proven and if he can score 12 goals in Ipswich town last season then there's a possibility that he could double the numbers in Chelsea. His presence alone might help Jackson improve cause by the time he's been benched on several occasions then he'll see reasons to sit up and fight for his place. Chelsea have signed Delap, do they still want to sign Osimhen too? I doubt they'll.
Personally I doubt Chelsea will look to add to their forward stock, Enzo Maresca currently has a few players in the same area. Delap could be the solution for next season, and Chelsea should encourage Jackson to leave, he is not good enough even as a rotation option. Meanwhile, Osimhen will not come if he is not guaranteed first-team football, besides Chelsea also have to be careful in their actions in the transfer window, they will likely have to streamline their squad to avoid potentially breaking FFP rules. Osimhen seems closer to joining Man United, Chelsea may have given up on pursuing him after disappointing last season. I see Napoli being too convoluted in the Osimhen transfer negotiations, but it is unlikely that Osimhen will be part of Conte squad next season.