Is it possible to grant another Elastic Cloud SSO user access to my Elasticsearch instance on Elastic Cloud?

Asking and answering my own question in case it helps others in the future.

For now, it is not possible to grant other Elastic Cloud SSO users access to an Elasticsearch instance on Elastic Cloud. However, you can add new users as native realm users in Elasticsearch or Kibana. Users can then log in to your Elasticsearch instance on Elastic Cloud using native realm credentials instead of Cloud SSO credentials.