Who can endorse content?
This differs based on if you would like to promote or certify content.
Any content owner with write permissions in the workspace where the content is located ie a user with an admin/member/contributor role can promote their content.
Only authorized members as selected by the Power BI admins are able to certify content. Content owners who are not authorized but would like to have their content certified need to follow their organization's guidelines about getting their content certified.