Since you already know what you are going to build (the existing business is the model) I would spend a fair amount of effort thinking about how you are going to take it to market. Assume you already built it - what are you going to do tomorrow morning to get it out there? If the answer to that question is not clear - spend a lot of time until it is.

Posting to HN and Product Hunt most likely won’t cut it, especially if a clone.

Cloning an existing business seems a lot more interesting if you have some unique method or access to penetrate the market where the current business is falling short.