This is one of 4 multi-cluster topologies we will eventually document (multi-primary, primary-remote, external-control plane and federation) under the general topic of "multi-cluster".

Community sail-operator documentation: https://github.com/istio-ecosystem/sail-operator/blob/main/docs/README.md#multi-primary---multi-network

Note that the above describes a "multi-network" setup, and there is also a (much simpler) single network setup documented upstream: https://istio.io/latest/docs/setup/install/multicluster/multi-primary/

Product documentation should cover both options.

Instructions for configuring Kiali with this topology will be part of OSSM-8266