Papijo Usage Report for H5P adds a read-only page under Tools that scans public WordPress post types for H5P shortcodes such as [h5p id="123"], [h5p id='123'], and [h5p id=123].
The report shows the H5P content ID, H5P title and content type when available from the H5P database tables, number of uses, posts or pages where each content item is used, and edit links to those posts or pages.
When the H5P contents database table is available, the report also lists H5P content items that do not have detected shortcode usage.
This plugin does not modify posts, pages, custom post types, or H5P content.