This is an ACME client for ESP (ESP32, etc) devices, so your IoT can fetch their own certificate for secure communication. ACME is a protocol (see RFC8555) for automatic certificate management. Sites such as letsencrypt.org allow you to obtain free (no charge) certificates in an automated way using the ACME protocol.
This is a client for dynamic DNS services, aimed at ESP (ESP32, etc) devices. Your node can use such a service to make its IP address known as a public DNS name, so you can find it, and use it from applications.