Access to a specific folder only in google drive using google picker

Question

I want the user to have the ability to grant access only to a specific folder in Google Drive. To achieve this, I'm using the drive.files scope and this simple code from the examples.

function createPicker() {
    var docsView = new google.picker.DocsView()
        .setIncludeFolders(true)
        .setSelectFolderEnabled(true)
        .setParent('root');

    const picker = new google.picker.PickerBuilder()
        .enableFeature(google.picker.Feature.NAV_HIDDEN)
        .enableFeature(google.picker.Feature.MULTISELECT_ENABLED)
        .setDeveloperKey(API_KEY)
        .setAppId(APP_ID)
        .setOAuthToken(accessToken)
        .addView(docsView)
        .addView(new google.picker.DocsUploadView())
        .setCallback(pickerCallback)
        .build();
    picker.setVisible(true);
}

async function pickerCallback(data) {
    if (data.action === google.picker.Action.PICKED) {
        let text = `Picker response: ${JSON.stringify(data, null, 2)}`;
        const document = data[google.picker.Response.DOCUMENTS][0];
        const fileId = document[google.picker.Document.ID];
        console.log(fileId);
        const res = await gapi.client.drive.files.get({
            'fileId': fileId,
            'fields': '*',
        });
        text += `Drive API response for the first document: ${JSON.stringify(res.result, null, 2)}`;
        window.document.getElementById('content').innerText = text;
    }
}

In the Google Picker, I select a folder.

I retrieve the folder ID, but when I try to retrieve the list of files, I get an empty result.

$service = new \Google_Service_Drive($this->googleClient);
$folderId = 'id';
$params = array(
    'q' => "'$folderId' in parents"
);

$files = $service->files->listFiles($params);
foreach ($files as $file) {
    printf("Found file: %s (%s)\n", $file->getName(), $file->getId());
}

If I select a file within the folder and then request the list of files again, I only get that file.

Therefore, my question is: Is it possible to use the Google Picker to obtain access to only a specific folder from the user? If not, are there any alternative options besides using the "https://www.googleapis.com/auth/drive" scope?