OpenId and AWS Cognito Federation Identity

I have setup my Okta application to use OpenId to communicate with AWS Cognito Federation Identities. I am able to authenticate with Okta and get an idToken and accessToken.

Where my problem lies is AWS needs a login URL for mapping when assigning credentials to a user. Here are other OpenId providers and their Login URLs.

// optional tokens, used for authenticated login
// See the Logins param for AWS.CognitoIdentity.getID (linked below)
Logins: {
    '': 'FBTOKEN',
    '': 'AMAZONTOKEN',
    '': 'GOOGLETOKEN',

Is it possible to configure trusts between OIDC Identity Providers (IdP). So, say you have an OIDC token from an external IdP X. With Cognito Federated Identities, one can add IdP X as a trusted IdP, and thus trust tokens that have been issued by IdP X?

Will I be forced to use SAML?