Only for declarative pipelines, forget it if you use scripted ones.

Prometheus + node/container exporters. + Grafana for dashboards I haven’t touched zabbix in years but last time it didn’t support very well dynamic scalations. Also all of them are focused on monitoring infrastructure, you need to pay if you want APM or UX.

Enterprise level, for APM I like datadog, much better than NR. For UX we use acoustic tealeef.