This is a complex problem. I considered this for many hours.

How does one securely restore their secure measures once their devices are lost?

Assume you lost your phone, laptop is also gone and your house burned down and your papers are gone with it.

I personally symmetrically encrypt my ssh keys and send them to my wife every six months or so. I also send them to a burner gmail account I use basic password auth with.

In a chaotic moment I can just ask my wife to download the file from her email and I can decrypt and ssh into my server where I store all files and important things encrypted.