Apart from 1Password 4, there used to be a lesser known 1Password for Windows Modern Alpha/Beta[1] which was a UWP app and supported local vault. The Windows Modern version is no longer in development as far as I know, but I hope they add local vault support to the 1Password 6 for Windows in the future (even though I'm a happy paying 1Password.com user).

[1]: https://www.microsoft.com/en-us/store/p/1password-alpha/9nbl...