In the documentation of ChirpStack I found information that it can integrate with InfluxDB, but I don’t see such a source in the sources list in the UI of InfluxDb. Is there anybody who knows how to integrate it into Telegraf?
Per the docs you linked to it sounds like there is a setting or option in ChripStack itself to send data to InfluxDB once you have the payloads decoded:
When configured, the InfluxDB integration will write device data into an InfluxDB database.
It looks like this LoRa App Server InfluxDB integration (with Grafana) - ChirpStack Application Server - ChirpStack Community Forum is an example and shows some screenshots of the InfluxDB integration page.