When will Cognito support LINE as another Identity provider?

I'm requested to develop a mobile app using React Native. So, I plan to use every services available on AWS. RDS, Lambda, API Gateways were selected and worked fine, but I struggle with Cognito and Amplify. In my case, most of my clients already has LINE user account and therefore they don't want to create another identity to use my app.
As far as I've known and tested, I have to use a third-party service, like auth0, as a middle agent to be able to config Cognito with LINE OIDC.
This's not a cost-effective way at all. Why do I have to pay 2 identity provider services for authentication?
Any suggestion? or work around?