var userPasswords = new List<Output<KeyValuePair<string, string>>>();
    foreach (var username in users)
    {
        //...
        userPasswords.Add(userLoginProfile.EncryptedPassword.Apply(p => new KeyValuePair<string, string>(username, p)));
    }

    UserPasswords = Output.All(userPasswords)
        .Apply(ps => ps.ToImmutableDictionary());
}

[Output("userPasswords")]
public Output<ImmutableDictionary<string, string>> UserPasswords { get; set; }