Databricks still hasn't committed to addressing this issue.

The only workaround is to get enrolled in the private preview for Dashboard Embedding with SSO (Embed with SSO Preview User Guide - Google Docs). This only works if you're already authorizing users with the same IdP SSO (e.g., Entra ID) and the users have the adequate access to the workspace, dashboard and SQL warehouse.

But for embedding dashboards for public consumption (non-Databricks users), the above won't work. One has to use a SP with a client secret.