Would be an excellent singing for you or any top side in the world as I’ve said repeatedly in this thread. With a fee north of £80m though, I would be concerned with how the other transfers you urgently need (specifically a striker, a centre back and possibly a goalkeeper) will be funded.
Brighton have shown no reported interest, however tenuous or weak the source, in any Manchester United players including youngsters, so it would seem to be the full fee or nothing. With respect, there is no evidence that the players Manchester United are expected to move on would be considered for our first team. Specifically Fred, Maguire, McTominay et al.
We have been consistently linked with Chelsea players however (Gallagher, Broja, Colwill, David Fofana) so there is perhaps some room for negotiation on that front, although I still think a P/X is unlikely because they so rarely happen in top level football.
I think Mount will be the guy you sign after all is said and done, but I’d rather have Caicedo if I supported Manchester United. He’s the business.