This simple snap updates the configured DuckDNS domain names every five minutes. Configure it by providing your token:
$ snap set duckdns-kyrofa token=<secret>
And configure your domain name list (comma-separated, no spaces):
$ snap set duckdns-kyrofa domains=domain1.com,domain2.com
That's it. The daemon runs every five minutes. Check the journal for output, including any problems:
$ journalctl -u snap.duckdns-kyrofa.duckdns.service