I'd say Bayern, PSG, United, and us are potential suitors. Barca & RM could be in the mix, but I think they both have their own stumbling blocks (Endrick joining the latter has muted such talk).
Bayern broke their traditional habits by buying de Ligt, & I'm sure they'd see Osimhen in a similar light. Also, they made it known that a CF is high on the agenda, with talk of even Kane circling around.
The key factor that could decide things is Osimhen's vocal admiration/desire to play in the EPL; he's built for it.