> You could create an app for the platform that you charge a subscription fee for or offer for free or whatever you want.

Interesting choice, I was thinking of a similar thing (if I ever decided to monetize) but instead take a cut of app sales (by providing the distribution channel) and having no base usage fee (for the desktop version). For the hosted version it would cost some amount bc it's hosted in a remote VM for the user. I guess in that way it would make sense to offer some amount of inference with the price for users that don't have an existing codex subscription (and non-technical users would never have an open router key anyway).