It is a good premise. My opinion would be to lean in to the gamification and less towards the visual novel. You may be tempted to make this into a straight shot visual novel with predefined characters that asks the player to click through and experience the story, though personally I would caution against that. I would encourage you to rather set this up as a game where the main character must earn her way out by selecting and serving clients. The player could then have to manage resources such as money (she wants to be free but a girl has to eat), energy (she has to rest at some point and cannot sustain to great a pace), and even something like a submissiveness that she could learn over time allowing the player access to even more options as the story progresses. I think the standard visual novel would work here as well, but I think that this premise leans well into a resource management game. A lot of us have played a lot of similar games where you have to manage a brothel, it might be interesting to manage yourself within a brothel. Regardless of what you decide to do I think you are off to a solid start.