If you did it with OpenGL I’m sure you won’t have any problem with Nigara.
The difference between OpenGL and Nigara is that with OpenGL you write thousands of lines of code. And with Niagra you only have to make a couple of clicks.
So I think just by watching a few tutorials on YouTube you will learn how to use Niagra very quickly. There are a ton of fluid tutorials on YouTube.
I understand that for a person who is used to writing code, he feels a certain aversion to using bluprints. But believe me that at the end of the day the difference is not that big.
Make it easy!!
Cheers!!