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.
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.