There is none yet.

If there was one, someone would write down the steps necessary and put them on the internet. But I have never seen a sound description of how to self-custody Bitcoin in a safe way.

The hardest part seems to not even be the one that currently creates all those problems - the hardware and software used. The hardest part is storing the key (for example a seed phrase). If anyone says they know a way to safely store Bitcoin, my first question is: How do you store the key?