Bitwarden Authenticator is a standalone app that is available for everyone, even non-Bitwarden customers.
In its current release, Bitwarden Authenticator generates time-based one-time passwords (TOTP) for users who want to add an extra layer of 2FA security to their logins.
There is a comprehensive roadmap planned with additional functionality.
Available for iOS and Android
Yup, most 2FA is just TOTP, which is a pretty simple, open standard and is hardware independent. All you need is a key (the QR code or the numbers) and access to a reliable time source and you can make a TOTP app on anything.
I use Aegis on my phone and Authenticator on Linux (some GTK app), and they both produce identical codes for the same key.