Not GP, but I’m assuming https://www.passwordstore.org/. Pass is a CLI password manager using Git and GPG to store and manage your passwords. I use it and sync passwords across devices through a git repo on self-hosted Gitea. Works really well if you’re comfortable with the CLI.

Also switched away from Google to Fastmail with my own domain about a year ago. Happy with the move, although Gmail still sees some activity because I never took the effort of migrating historic mails and all non-primary accounts.