You can actually do this by enabling the option:
"Provisioners using this Onboarding Template can view and edit each other's records" on the Common tab of the Onboarding Template.
That way, any provisioner who is assigned that template can also view/modify records made by someone else, using the same template.
If you have multiple templates, but want one user to be able to see them who ISN'T admin, you would create the provisioner account, enable all the templates you want that provisioner to be included on, and then also check that same "can view each other's records." That provisioner should then have access to any and all guests/devices created under the associated onboarding templates.