Build secure web frontend/portal for admin APIs

I currently run a SMS platform where I don't expose the admin interface to customers. I would like to create a secure admin portal for customer self-service. The admin functions are currently exposed as JSON webhooks on the local system and I would like the admin portal to call these webhooks. The portal would need to do the following: 1. Authenticate the admin user using a federated identity service, i.e. I don't want to store or manage credentials. 2. I would like to solely maintain a table of role mappings by username/email address. Database engine is MariaDB, though the mapping could be maintained elsewhere. 3. Perform the following admin functions: a. modify account details b. create user c. modify user d. generate new api key for user e. transfer credit from account to user or vice versa 4. The authentication will map to an account id and role access will limit/allow access to certain functions. 5. Information will be retrieved via webhook call (returned in JSON) and changes will be posted in JSON format. I am happy to modify the webhooks to best integrate with the admin portal. For reference, the following information should be able to be displayed and/or edited: Account - ownerName (varchar(100)) - The name of the account owner - ownerEmail (varchar(100)) - The email address of the account owner - alertLevel (integer) - The credit level at which low balance alerts are generated - accSend (varchar(16)) - The text (or number) used when sending SMS User - Name (varchar(100)) - The name on the user account - Email (varchar(100)) - The email address used for sending/receiving alerts - smsSend (varchar(100)) - The text (or number) used when sending SMS (can be null) - alertLevel (integer) - The credit level at which low balance alerts are generated Additionally, the portal admin user should be able to regenerate an API key for a user (via webhook call which returns the key) and only displays it once. For transferring credit, the function will call a webhook to get the balances and allow for moving credit between account and any user. portal admin should be displayed a total (across account and users) and be able to set credit levels across all up to the total, i.e. if total credits across account and users is 100 then the admin can allocate up to 100 credits across all entities. Initial values should be whatever was returned by the webhook. Updates should be to any modified balances and will be set by calling a webhook. The platform is currently built using nodejs and APIs are behind a reverse proxy (nginx). System runs on Debian Linux 11. Preference would be for the admin portal to be either able to be deployed to GAE as a standalone app which calls the APIs or as a nodejs/python app which will run locally on the machine. In either case, HTTPS will be handled via nginx so does not need to be considered in the app itself.