You do not need a static IP address or dynamic DNS if your domain registrar provides a REST API. My current registrar is Porkbun and they have a REST API. I simply have a cron job that regularly checks if my public IP[^1] differs from the domain's A-record. If it does, it updates the record to match the public IP address using their API.
[^1]: I use Porkbun's ping endpoint to obtain my public IP. There are also alternatives such as Ipify.
Use declarative systems and software, where the configurations files themselves are the documentation. For example, I use Guix and Podman. The entire OS is described in a Scheme file and all the services are described in a YAML file. I just need those two files to get an overview of the entire setup.