Metricbeat Visualizations

Is there some repository where I can get some preconfigured system metric visualizations?

Because from the information I gathered, it seems Metricbeat is not delivering any dashboards anymore.
At least in my Metricbeat 7.12 installation I can’t see any in opensearch.

Wouldn’t suggest using OpenSearch/Elasticsearch for metrics at all, you will regret it when you need to run any kind of scale or long term retention. This is why most people are using Prometheus for this use case. It’s very popular and has significant advantages over using MetricBeat.

So you would suggest having a prometheus environment with another dashboarding app like Grafana alongside the opensearch stack?

I was thinking to get all inside the opensearch stack for not having the need to maintain two different systems.

Yes, that would be my current suggestion. However the vision we (at at least) have for Opensearch Dashboards includes support for PromQL queries and better time series visualization which would eliminate the need for Grafana over time and have a unified front end which remains fully Apache 2.0 open source. AWS shares many of the same visions for the project as well.