The likelihood that someone would be able to do this in 50 years time, without your company still around? Close to zero.
Passwords, even ssh keys and passkeys, are little pieces of plain text. If you think needing a specialised sdk or cli to retrieve plain text is a good software architecture, I think we see the world quite differently.
That's the exact reason it's open source, so it would still be possible to access your data in such an event.
We clearly see things differently but I think using computers to make our lives easier is worthwhile and storing/managing our secrets securely, effectively and conveniently is better managed by software than some ad-hoc setup.
Nitpick, passkeys are not text, they are binary blobs.
It's truly local first and will work fine in an airgapped situation.
It's also designed to be self-hostable[2], is open source [3] and the API is well documented[4].
[1] https://saveoursecrets.com/ [2] https://saveoursecrets.com/docs/cli/self-hosting/ [3] https://github.com/saveoursecrets/sdk [4] https://docs.rs/sos-sdk/latest/sos_sdk/