Bitwarden, especially the Flatpak, is annoying to configure on Linux. I couldn’t find all the info in one place so here it (hopefully) is. No guarantees that this will work but it seemed to for me.

Step 1. Enable SSH agent in Bitwarden

Enable the SSH agent in Bitwarden by going into settings and check the tickbox.

Step 2. Edit your bashrc and profile files

Add to ~/.bashrc or your shell config file. In order for Git commit signing to work in VSCode you need to add the following command to ~/.profile too.

export SSH_AUTH_SOCK=/home/<user>/.var/app/com.bitwarden.desktop/data/.bitwarden-ssh-agent.sock

Step 3. ~/.gitconfig

Add this to your gitconfig:

[user]
        name = <name>
        email = <email>
        signingKey = <your ssh key>
[commit]
        gpgSign = true
[tag]
        gpgSign = true
[gpg]
        format = ssh