My experience with tools like these on Kubernetes, even with something stable and widely used as e.g. certmanager, is that in the end something still breaks and

My experience with tools like these on Kubernetes, even with something stable and widely used as e.g. certmanager, is that in the end something still breaks and you still need to get familiar with all the building blocks. In comparison if you use managed services like the AWS Certificates service you have less friction and less risk for something to break.