OIDC Access Token to SAML Assertion

We have OIDC Web APP which which is a bridge between desktop and real web app. We make use of access token to federate ODIC Bridge App, Desktop and real web app. Now, we have a SAML App but cant find a way to generate saml assertion from access token that is something we can used for SSO. we tried to make use of OIDC to SAML bridge but it needs a valid OKTA session. The only option we have is to make use of access token to perform sso across all three web apps.

Is there any api there where we can generate saml assertion on behalf of access token ?

I am open for other alternatives as well.