Read the article, it’s all covered there. Open source password managers like bitwarden and keepass are ideal, but passkey support and integration with the OS is not there yet. With text passwords, you always had to fallback of copy and paste. With passkeys, OS integration is crucial.
My guess is that it may happen, or the big companies like Google or Apple can keep shifting the standards to keep the open source options outdated, like what Google already does with web standards.