Except OpenRouter sees all your prompts, sends your requests to different providers with pinky promises that they dont use your data, and is therefore a non starter for any company who cares about compliance.
If Stripe wants to spend 7 billion on a glorified reverse-proxy-api-gateway go ahead. I can here and now, guarantee to be able to reproduce all their functionality in 3 months, and for less than 10 million dollars. And Stripe internal engineering teams should be able to do better, as I will do it in the evenings only :-))