There is no need for your described complexity. More advanced FIDO devices like the Ledger allow you to backup the initial random seed allowing you to create a

There is no need for your described complexity. More advanced FIDO devices like the Ledger allow you to backup the initial random seed allowing you to create a duplicate device from the backup any time you wish. No sites you signed up with will know or care that you swapped devices as the new device will generate identical keys via a deterministic KDF from the seed. You can put this seed far away and would only ever need it when you wish to replace a lost or broken authentication device. Aside: no US major banks issue safety deposit boxes anymore other than wells fargo which will stop issuing them soon as well.