Alerting or control plane or both? If alerting is AWS only, I'm very sad. What happens if there is a global AWS outage? Never been one yet, but never say never.
If your service needs to survive a global aws outage, you just can't run with any saas. So many of these companies are single regioned in AWS. Auth0, Okta, Datadog, many others put customers in a regional box, and if that region goes down, all of those customers go down.
