You mentioned not trusting Google, but FWIW, Google Authenticator added support within the past year for multiple devices: https://www.theverge.com/21410260/goo

You mentioned not trusting Google, but FWIW, Google Authenticator added support within the past year for multiple devices: https://www.theverge.com/21410260/google-authenticator-2fa-how-to-phone-security-iphone-android https://www.theverge.com/21410260/google-authenticator-2fa-h...