Keybase is not open source. The whole premise is undone in the second sentence.

Not having a cross platform, easy to use, open sourced password manager has always been a pet peeve of mine

I’ve personally had great success with Keypass.

wow, i could have used this article a couple months ago, i started piecing all of these together and gave up

found https://github.com/dani-garcia/bitwarden_rs and set it up on a spare VPS and haven’t looked back