My heart went in my throat when I read your title, I assumed the worst, meaning crypto keys, I'm glad it was just your house keys.

A “decentralized authenticator application” is a good idea. Make things simpler, yet more secure.

I struggle between attaching assets to a key that I own but I could lose; and attaching assets to my identity which I own but I have to trust that the "custodian" does not lose to somebody else or locks me out.

As I get older, and I start to forget things, I'm hoping there's a solution to where I can have the best of both worlds. If I lose my keys I can recover them with my identity without the other party or app having access to those keys. I think safe deposit boxes work from that concept, but it can be physically inaccessible. Maybe a biometric safe in one's house or 24/7 accessible secure location.