Yes, all the options you mentioned are possible, but the hosting model differs.
For Datadog and Dynatrace, the usual setup is SaaS, so in most cases you do not need to host them yourself.
For Prometheus + Grafana, the open-source setup is usually self-hosted, so you would typically need your own environment. If you want a managed option, Grafana Cloud is also available.
For Mendix Dedicated Public Cloud, the general flow is:
So in simple terms:
If your priority is easier setup and less infrastructure management, Datadog, Dynatrace, or Grafana Cloud are easier options. If you want full control and prefer open source, Prometheus + Grafana is the usual route./