Possible to list all realms as non-master service account/user?

I have a multi-tenant setup where each tenant is configured with a realm on Keycloak. I’d like to be able to use the list of Keycloak realms as the source-of-truth for the tenants in the system. I am giving backend services their own client with service account in each realm. However, how can I grant them the ability to query all of the realms? Would they need a service account in the master realm or is there some cross-realm access I can grant them?