I don't think United have to go for broke on either of these players, especially considering the transfer budget and need for other quality players in the starting XI and squad.
I don't claim to know who these alternatives are. Just from my observations of Napoli and Osimhen this season, a more well rounded player like Kane, Rooney, Alvarez, Watkins, would suit the squad....unless EtH switches the team's overall attacking approach next season to accommodate one primary CF...which I have a hard time seeing based on Marcus and type of players on the wide areas United have.