The service differences between native and permissionless integration:

Native Integration is a program we offer to partner teams, providing more reliable in-house infrastructure and customer support, as well as full support across Keplr products, including Keplr Dashboard, Validator Dashboard, Multisig, and Mobile. If this is what your team is looking for, please reach out to our partnerships team for further discussion.

That said, Non-native integration is more than enough to make your chain usable in Keplr Extension. By implementing the Suggest Chain feature in your frontend, your dApp users can easily add and use your chain in Keplr Extension. Alternatively, you can register your chain information in the Keplr Chain Registry, which allows users to select your chain under Non-native chains in the Select Chains page of Keplr Extension.