As a result of @Thra11 suggestion, my current shell.nix looks like this:
with (import <nixpkgs> {});
let
kirigami = libsForQt5.kirigami2;
qt = qt5.full;
in
mkShell {
buildInputs = [
clang-tools
clang
cmake
extra-cmake-modules
libsForQt5.appstream-qt
libsForQt5.kcoreaddons
kirigami
libsForQt5.ki18n
qt
];
shellHook = ''
export QML2_IMPORT_PATH=${kirigami}/lib/${builtins.replaceStrings ["full-"] [""] qt.name}/qml
'';
}