"Show HN is for something you've made that other people can play with. HN users can try it out, give you feedback, and ask questions in the thread."
Looks like you can try it out so not sure why do you think it's not good for ShowHN?
This sign-up page especially rubs me the wrong way as it uses a dark pattern: It grabs your email address first and then tells you that you cannot proceed without entering your credit card details.
My product has not been used yet, just put it live yesterday. My idea here was just to get general feedback, like yours.