In terms of something

It should be "In terms of quality ingredients, ...".

You seem to have answered your own question! It means "As far as quality ingredients are concerned, this is the best ice-cream you can buy."

In other words, if one is assessing ice-cream based on the quality of the ingredients it contains, then this is the best.

Sorry, I forgot to add "s"

Is there any other way to say this?

i think you already have the best ways to say it. It clearly states that if we're talking about quality ingredients, then this ice cream is the best! :-D

So they're comparing two ice cream, and they decided to choose the one with better ingredients, right?

xHealthY
So they're comparing two ice cream, and they decided to choose the one with better ingredients, right?

Mr Wordywhen all the ice-creams are ranked in this way, "this" one comes out on top.

that's right. so, the sentence suggests that the ice cream has the best ingredients. But, in terms of the color,it may not have the best color.(for example)

So I can work as a CNA, and do something else relating to nurse?

Could I say -

So I can work as CNA, and so something else in terms of nurse?

xHealthY
So I can work as a CNA, and do something else relating to nurse?

Could I say -

So I can work as CNA, and so something else in terms of nurse?

Neither "relating to nurse" nor "in terms of nurse" is possible.

Assuming you are talking about things connected with the nursing profession, you could say "... do

xHealthYIn terms of (the quality of the) ingredients

When you consider ingredients as a way of measuring (the ice cream), (this is the best ...)

In terms of size, ... = When you consider size as your measure, ...
In terms of quantity, ... = When you consider quantity as your measure, ...
In terms of brightness, ... = When you consider bright