Moin,
the UCS Dashboard is based on Grafana and Prometheus: 15.1. UCS Dashboard — Univention Corporate Server - Manual for users and administrators
You should be able to make use of them in their full capacity, so everything that provides Prometheus-compatible metrics and can be reached by the database for scraping can be monitored. This includes Debian and all other Linux distributions where the Prometheus Node Exporter can be installed.
Additionally to the manual above I once wrote a short tutorial to add custom services: Best Practice: Monitor additional services with the UCS-Dashboard
Best regards
Jan-Luca