FressRSS/app/views/helpers/export/articles.phtml

<?php
declare(strict_types=1);
/** @var FreshRSS_View $this */
$username = Minz_User::name() ?? Minz_User::INTERNAL_USER;

$options = JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE;

$articles = [
	'id' => 'user/' . str_replace('/', '', $username) . '/state/org.freshrss/' . $this->type,
	'title' => $this->list_title,
	'author' => $username,
	'items' => [],
];

echo rtrim(json_encode($articles, $options) ?: '', " ]}\n\r\t"), "\n";
$first = true;

if (empty($this->entryIdsTagNames)) {
	$this->entryIdsTagNames = [];
}

foreach ($this->entries as $entry) {
	if (!$this->internal_rendering) {
		/** @var FreshRSS_Entry */
		$entry = Minz_ExtensionManager::callHook('entry_before_display', $entry);
	}
	if ($entry == null) {
		continue;
	}

	$feed = $this->feed ?? FreshRSS_Category::findFeed($this->categories, $entry->feedId());
	$entry->_feed($feed);

	$article = $entry->toGReader('freshrss', $this->entryIdsTagNames['e_' . $entry->id()] ?? []);

	$line = json_encode($article, $options);
	if ($line != '') {
		if ($first) {
			$first = false;
		} else {
			echo ",\n";
		}
		echo $line;
	}
}

echo "\n]}\n";