Android Kotlin - Credential Manager - Make use of PasswordCredential and PublicKeyCredential

Question

So far I have set up this:

is CustomCredential -> {
    if (credential.type == GoogleIdTokenCredential.TYPE_GOOGLE_ID_TOKEN_CREDENTIAL) {

and it's actually all I need.

But what are the other two possibilities:

is PublicKeyCredential -> {
    val responseJson = credential.authenticationResponseJson
}

is PasswordCredential -> {
    // Send ID and password to your server to validate and authenticate.
    val username = credential.id
    val password = credential.password
}

?

When I test the login, I don't see anything that I could do to enable/use those.

This is the request:

val googleIdOption: GetGoogleIdOption = GetGoogleIdOption.Builder()
    .setFilterByAuthorizedAccounts(false)
    .setServerClientId("keyyyy")
    .setNonce(hashedNonce)
    .build()

val request: GetCredentialRequest = GetCredentialRequest.Builder()
    .addCredentialOption(googleIdOption)
    .build()

Do I need to add something to the request to enable those?

The google docs are unclear since they are as always like a puzzle in which all informations are scattered on 1000 different pages.