The easiest word to use, and the word that has the most chance of being adopted by the general public as a singular pronoun is "they". The technically correct term is "It" but somewhere along the line in the evolution of the English language it became considered dehumanizing. "One" when used as a pronoun is considered awkward and overly formal.
You can't just invent a word and expect everyone to automatically start using it.
Especially when you can't even get the trans community to agree on which invented pronouns to use, let alone the general public. Language doesn't work that way. I can guarantee you that if you actually used one of those pronouns to a stranger on the street, whoever you're talking to would look at you like you suddenly grew 4 eyes, and then ask you to clarify what you just said, completely interrupting the flow of the conversation.
Plus, which is actually easier to say; "They went down the street." or "Zie went down the street"?
If you are going to put in the effort to try and create a word as commonplace as a pronoun, then it needs to flow off of the speakers tongue in a natural manner. The entire point of language is effective communication, and if something as simple as a pronoun cases the speaker to stumble over their words for even a second, then that word is counter-intuitive.
I'm not saying that you shouldn't use a person's preferred pronouns, but expecting those words to automatically get adopted into the popular lexicon is unrealistic.