A physical device which is not your computer stores some secret information which can authenticate you. This can be passwords, passkeys, GPG keys, your retina etc.

The physical device can be password protected. So you have two step authentication: 1. your physical device 2. your password to that device

Phones are currently being promoted for various reasons, but I believe something like Yubikeys or other FIDO2 fobs will be a better device. You can have multiple of them, you can store one of them in your bank safe. Someone stealing it of you is proper theft which can be traced in a usual manner by police. Stealing is not enough because you still need the password. The difficulty of asking you for password remains equal to difficulty of hitting you with a wrench. You don't need to remember stuff anymore, because you can just use your physical keys. You will need to travel with those keys, but its just same as your house keys. It is probably an extra key in your key fob.

To add to it, the U2F/FIDO2 standard will make it vendor independent, and so no lock-in.