1 click to deploy ... That's it!
Well maybe not completely free but only a few pennies if you are already using AWS Route 53. Like $0.75/month max.
Supports IPv4 and IPv6. Provides the same interface as DynDNS (dyn.com) so it should work as a drop-in replacement. You can configure a domain name and it will automatically configure everything needed to make the API accessible.
yo1ddns is an AWS CDK app. CDK apps generate AWS CloudFormation stack templates. CloudFormation stacks allow you to easily manage a sets of AWS resources. CDK allows you to build your stacks with code rather than configuring in JSON/YAML which is much better. The CDK CLI also allows you to easily deploy and update your stacks.
The stack consists of an API Gateway, 2 Lambdas, and a few roles and such to tie everything together. One of the Lambdas serves as an API authenticator to support HTTP basic auth. The other handles updating Route 53 DNS records with new IPs. The API proxies requests to the Lambda. Pretty simple.
I added a little bit of code that transforms the CDK generated template into a standalone template which is what powers the 1-click deploy link. Basically a template made to be configured and deployed directly from CloudFormation rather than through CDK.
Checkout the GitHub page for more information on how to build and deploy the CDK app.