I just want to be honest with the people who will play my game.
Don't be honest, be transparent. Be open about the process, deadlines, etc and properly communicate with people, but don't just openly state "I want money, lol" because most will find this annoying.
The reason I did this “pay me this amount to let me start making new” is because I wanted to get donations, on my non-NSFW ko-fi account. This is all solely because my country doesn't allow the buying and selling of NSFW content, so I can't make NSFW ko-fi accounts.
I mean, if anyone bothered investigating then they would establish causality pretty easily. Having some plausible deniability is good, but it might actually be worse for you here since "I made this game because I honestly need money, and after releasing chapter 1 (v0.1) I plan to postpone making the game until I get enough donations from you guys." sounds like a transaction. I am not sure what your country's laws are or whether you can consult a lawyer on this (or if it will even be a good idea to do so), but the way you worded that statement can easily come to bite you in the ass.
I decided to do this type of donation after I saw a female streamer. She promised to do a cosplay if the donation reached its target. I was just trying to come up with the same concept. I apologize, because I don't think this is such a bad thing. But, I don't intend to stop this kind of donation concept because this is the only solution I found.
What I said regarding optics still stands, but stating that this sort of approach is the safest option you have legally is very different from "I need money, lol".
unless the game is actually a really good proof of concept and gets steam
I doubt that it will get Steam, this game is made with Koikatsu (quality is not that great either, the characters have bulbheads, use the default ingame shaders, use preset poses, etc) and while Illusion did go under, I am still not sure of the legality of publishing this game on Steam.