Firebase身份验证没有用于Amazon登录的内置提供程序.这意味着，要允许使用Amazon帐户登录Firebase，您必须创建一个自定义提供程序.

Firebase Authentication has no built-in provider for Amazon sign-in. That means that, to allow signing in to Firebase with Amazon accounts, you'll have to create a custom provider.

当前不支持将自定义提供程序帐户链接到现有帐户(从内置提供程序中).但是，如果您查看此Github线程，则有一些不错的信息如何通过使用自定义声明或其他机制来实现相同目标.

Linking custom provider accounts into existing accounts (from built-in providers) is not currently supported. But if you look at this Github thread, there's some good info on how to accomplish the same by using custom claims or another mechanism.