We used Datadog at my last place to do monitoring/alerting type things. It's pretty pricey in my opinion and the amount you get out of it just wasn't worth it for us, but it might be for you. Another option is to host Prometheus for this.
Datadog is good for metrics, but I'm more curious about the deployment side of things. For example, let's say I just made an update to a service's API that requires deploying new versions of 3 microservices. I want to (1) be able to locally deploy and test the 3 new versions, and (2) deploy all 3 versions at the same time. This ends up being super tedious because I have to do a lot of manual work just to push a (potentially minor) update.