Currently, in progress, more or less.
Note that on this set of examples, steps 1, 2 and 3 are incremental, therefore they use resources set up in each one of the previous examples.
Example of Alert Manager could be a simple "when X service has 80% of 503, rise alert"
Related link
https://github.com/istio/istio/tree/master/samples/addons
https://github.com/prometheus-operator/prometheus-operator
https://istio.io/latest/docs/ops/integrations/prometheus/
https://istio.io/latest/docs/ops/integrations/prometheus/#tls-settings
https://www.reddit.com/r/istio/comments/usld1h/istio_mtls_and_prometheus_the_definitive/
https://superorbital.io/blog/istio-metrics-merging/ <--- Interesting read