Earlier quoted context omitted.
If we're talking OTP/TOTP -- it's all the same. Even if a provider instructs you to use a specific app, e.g. Google or Authy, you can simply scan the QR code with whatever authenticator app you're using. All the QR code does is encode a URI containing the secret and issuer.
This is simply not true. Just today an app asked me to use Microsoft Authenticator, and scanning the QR code with Google Auth and Authy didn’t work, earning me an “Invalid QR code” error and forcing me to install the app from MS.
There's nothing complicated about otpauth provisioning URIs i.e. what's encoded into the QR code.
[0]: https://shkspr.mobi/blog/2022/05/why-is-there-no-formal-spec...
[1]: https://github.com/google/google-authenticator/wiki/Key-Uri-...