1Password is working on passkey support already (https://www.future.1password.com/passkeys/) and I imagine others will follow suit. Vendor lock-in isn’t part of the spec, it just happens that in these early days, the OS-level authenticators are the main ones implemented (as are other hardware authenticators).
In the mid to long term (e.g. by the time websites start supporting this), I don’t think vendor lock-in will be a problem. It’s no worse currently than chrome or iCloud Keychain being your password manager, which has been part of the landscape for a very long time. Like password managers, there will be other options. The benefit is that unlike passwords, there is a standard API for “autofill credentials” rather than using an extension to update the DOM.