How about using a password manager? I think KeePassXC is useful with its keyboard shortcuts.

Password managers
We suggest that you use a more robust solution than the built-in password manager available in the browser:

• Bitwarden: open source password manager that allows for synchronization across multiple devices.
• KeePassXC-Browser: official browser plugin for the open source password manager KeePassXC.

Recommended Addons – LibreWolf
librewolf.net/docs/addons/#password-managers