Pod to pod route / communication? Multiple localities


I have seen following blog:

Multiple data centers == localities.
–> How to have “pod to pod routes/communication”, with official “k8s” means?

Would following be one alternative?

Obsolete: Pod specific ingress --> Pod specific service --> Certain crdb pod

–> https://kubernetes.github.io/ingress-nginx/user-guide/exposing-tcp-udp-services/
Is following possible?
Pod specific config map --> Certain crdb pod

Is it possible join crdb nodes through such config maps between localities?

Are there possible problems with such setup?
Any possible stability problems?

Checking, are there pod specific selectors in config maps.

E.g. svc-0 chooses crdb-pod-0.

Can it work? Is it like:
Pod specific config map --> Pod specific svc --> Certain crdb pod

Pod specific config map may make it visible in ingress?