Related to this article that explains the use case better than I can do in short order here.
Does Okta have support or will it have support for rfc8693 Token Exchange? This is now a proposed standard (not a draft) and at such point it is not uncommon for vendors to start adoption.
In addition to/as a part of the enhancement to add support for the On-Behalf of Flow, we are looking to support Token Exchange, but we do not have an ETA at this time about when this will be available. This Okta Idea tracks this request and will be updated when we have more details about the implementation.
You may want to reach out to your Okta Account Manager or Customer Success Manager so that we can track your specific use case as we begin to plan building this out.