t-minus365 has details on how to consent to apps on behalf of customers, without having to consent using admin accounts in the customer tenants. Use the REST API examples, not the PartnerCenter stuff.
https://tminus365.com/my-automations-break-with-gdap-the-fix/
https://tminus365.com/gdap-multi-tenant-automation/
https://tminus365.com/how-to-leverage-microsoft-apis-for-automation/