How can I enable online accounts (like google) in kde?

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1

I have the following in options set in my nixos flake.nix file:

{ config
, options
, lib
, pkgs
, ...
}@inputs:
let
  inherit (builtins) pathExists readFile;
  inherit (lib.modules) mkIf;

  cfg = config.modules.desktop.kde;
in
{
  options.modules.desktop.kde =
    let
      inherit (lib.options) mkEnableOption mkOption;
      inherit (lib.types) nullOr path;
    in
    {
      enable = mkEnableOption "Enable the KDE desktop environment";
    };

  config = mkIf cfg.enable {
    services.xserver.enable = true;
    services.xserver.displayManager.sddm.enable = true;
    services.xserver.desktopManager.plasma5.enable = true;
    programs.dconf.enable = true;
    programs.kdeconnect.enable = true;
    security.pam.services.sddm.enableKwallet = true;
    environment.systemPackages = with pkgs; [
      libsForQt5.ark
      libsForQt5.bismuth
      libsForQt5.packagekit-qt
      libsForQt5.discover
      libsForQt5.kio-gdrive
      libsForQt5.plasma-integration
      libsForQt5.plasma-nm
      libsForQt5.kalendar
      libsForQt5.accounts-qt
      libsForQt5.mauikit-accounts
      libsForQt5.kaccounts-integration
      libsForQt5.kaccounts-providers
      libsForQt5.signond
      libsForQt5.qoauth
      libsForQt5.calendarsupport
      libsForQt5.qtspeech
      libsForQt5.sddm
      libsForQt5.sddm-kcm
      libsForQt5.flatpak-kcm
      libsForQt5.kcmutils
      # Keyboard
      libsForQt5.qt5.qtvirtualkeyboard
      maliit-keyboard
      maliit-framework
      # spellcheck
      aspell
      aspellDicts.de
      aspellDicts.en
      aspellDicts.en-computers
      aspellDicts.en-science
    ];
  };
}

I am unsure if this is the preferred way of installing KDE on NixOS. I followed the guide on the NixOS wiki: https://nixos.wiki/wiki/KDE. My problem now, is that I cannot add a Google-account on under KDE Settings > Online Accounts > Add New Account. I get the following error in the settings gui:

There was an error while trying to process the request: Authentication method is not known

And if I launch the settings using my cli, I get the following output in the terminal:

> systemsettings5
# [...]
file:///nix/store/82xhn3s7l1p4jsmi861a6jvg5f9qyci7-kirigami2-5.106.0/lib/qt-5.15.9/qml/org/kde/kirigami.2/templates/OverlaySheet.qml:603:17: QML ColumnLayout: Binding loop detected for property "height"
"google"
Looking for plugin ""
Starting auth session with "oauth2"
Error:
	 "Authentication method is not known."

is there some application I am missing? My error already changed after I added the following to my environment.systemPackages:

libsForQt5.kaccounts-integration
libsForQt5.kaccounts-providers
libsForQt5.signond
libsForQt5.qoauth

Before that, I did not even get an error in the settings app when trying to add a Google account. It just did not do anything.
This leads me to believe, that I am still missing crucial system packages. Does anyone here know what I would need to change? Thank you a lot in advance.