Back in Wano Kaido said that Awakening occurs when your mind catches up to your Devil Fruit, and while that is a description, it’s still pretty vague in my opinion.
However in Chapter 1069 Vegapunk talks about how Devil Fruits are born from wishes, so likely the wish to be free or something like that created the Nika fruit.
Now here’s my theory: for you to awaken your Devil Fruit, you need to embody the original wish that created the fruit, or at the very least understand it. Luffy couldn’t awaken his Devil Fruit until he truly desired to be a liberator, dreading the future of the people of Wano under Kaido’s rule if he lost.
This could also explain why awakening Zoans is so dangerous, as wanting to become an Animal will regress your mind if not careful. My theory is that Lucci was not overwhelmed by the Zoan’s innate nature because he already represents it well. His fruit is that of a leopard, a predator that wants to kill, Lucci already just wants to kill, he is violent and serves the World Government so that he can kill who they order him to, so when he awakened he was not overwhelmed by the fruit’s nature because that was already his nature.
*Theory by nicentra