[Encrypt-Keeper]

It depends on the set of credentials. Your primary email address, your access to 1Password, things of that nature can and should be stored in a 2FA app on another device. But the majority of 2FA codes for most websites are fine to be stored in your password manager. This way you can enable 2FA on every site you use, without the inconvenience, but you can reserve the extra security of a second device for services that would be critical failure points for you.