Help creating a package

Hey, I’m currently trying to package tokodon, a kde mastodon klient. I have the following nix expression

{ mkDerivation
, lib
, cmake
, extra-cmake-modules
, kcoreaddons
, kconfig
, ki18n
, kirigami2
, kdbusaddons
, kitemmodels #TODO
, kwindowsystem
, plasma-framework
, qtkeychain
, qtmultimedia
, qtwebsockets
, qtquickcontrols2
, qqc2-desktop-style
, wrapQtAppsHook
}:
mkDerivation {
  pname = "tokodon";
  nativeBuildInputs = [
    cmake
    extra-cmake-modules
    wrapQtAppsHook
  ];
  buildInputs = [
    kirigami2
    kconfig
    ki18n
    kcoreaddons
    kdbusaddons
    kitemmodels
    kwindowsystem
    plasma-framework
    qtkeychain
    qtmultimedia
    qtwebsockets
    qtquickcontrols2
    qqc2-desktop-style
  ];
  meta = with lib; {
    description = "A modern [Mastodon](https://joinmastodon.org) client.";
    homepage = "https://invent.kde.org/network/tokodon";
    license = licenses.gpl3Plus;
    maintainers = with maintainers; [ laalsaas ];
  };
}

(It’s in plasma-mobile, so i don’t have to specify src, use a modied mkDerivation, etc, see here.)
During build, cmake produces this output:

-- Looking for shmat - found
-- qmlplugindump failed for org.kde.kitemmodels.
-- Could NOT find org.kde.kitemmodels-QMLModule (missing: org.kde.kitemmodels-QMLModule_FOUND)

However, it still builds the application, but the resulting binary is only partially applying the platform theme. How can i make cmake find the KItemModels?