Is there an idiom for: "a list of things that you know will not be completed but you are asking anyway"?

Sometimes in a written text I express a ton of things I would desire for something to have even though I know it is absolutely impossible to fulfill those desires.

For example in Spanish we can use: "La lista de los reyes magos" which means something along the lines of: "Santa's letter". It has a small component of irony in it.

The purpose in the context I'm using the sentence is: "I know that I'm asking for too much. I'm adding a lot of requirements for you to have more context in the direction I want to take. I know this is unfeasible.". That is why I want to give that small component of expressing that the result is impossible to reach.

That sounds like a wish list.

a list of things you want, often things that you know you cannot have: A new car would be top of my wish list. — cambridge.org

or

: a list of desired but often realistically unobtainable items M-W

I don't know of such an idiom, but it's certainly "wishful thinking".

You could call your list a Pipe dream, an unrealistic hope or fantasy. It is likely an allusion to the dreams experienced by smokers of opium.

When people express wishes for things highly unlikely to happen, one proverb I've heard (and used) is

"If wishes were horses, then beggars would ride."

It's a very old proverb meaning that if wishing could make things happen, everyone, even the most destitute people, would have everything they wanted.

I know of nothing more specific to impossible dreams put to paper than these.

"exercise in futility" may fit.

That is what they used to describe a complex database job I was assigned as busy work one time. And no, didn't finish it.

It doesn't specifically refer to a list, but "pie in the sky" seems to have the right sense:

something good that is unlikely to happen: I wanted to be a major league baseball player, but I knew it was probably pie in the sky. -Cambridge Dictionary