All these sites are platform-neutral. What you are selling is not applications, but keys to applications, tied to specific IMEIs. Therefore, there is no need to provide a Maemo-specific app shop. In fact, you can place your applications into Extras Non-Free, and let people download them from there, while selling keys separately.

You are not Nokia, so you will not "solve" anything related to Ovi store. Simply ignore it. You can sell applications through a dozen other channels available on the Net.

If you really want to provide another distribution channel and charge developers for using it, you should carefully consider what unique value your channel will provide when compared to the existing channels.