Hello, could the attack from Ferocity, be the Attack included in Nexu's Pounce ???

No, Pouce is a special action while Ferocity allows you to perform an attack, not a special action.

Ferocity doesn't grant an action, it only allows to "perform an attack". When a figure "performs an attack", it is performed with the attack type and attack dice specified in the deployment card.

RRG, Attacks said:

Figures perform attacks to attempt to defeat hostile figures.
Each attack uses an attack type (Melee: melee or Ranged: ranged ), attack
dice, and surge (surge) abilities. For a hero, this information
is found on his weapon Item card. For any other figure, this
information is found on its Deployment card.