Photonic takes the WordPress gallery and super-charges it with a lot of added functionality. It adds support for several new sources and parameters to enhance the content and look-and-feel of your galleries. It supports Flickr photos, Albums (Photosets), Galleries and Collections, along with Google Photos photos and albums, SmugMug folders, albums and images, Zenfolio photos, Photosets and Groups, and Instagram photos. You can also set up authentication so that visitors can see private and protected photos from each provider.
When used without the Gutenberg editor Photonic by default overrides the gallery shortcode. In case you happen to be using a theme or plugin that already overrides the gallery shortcode, Photonic provides you with the option to use your own shortcode for Photonic galleries. This lets your plugins coexist. Bear in mind that if you deactivate Photonic you will have to remove all instances of this custom shortcode, something that is not required if you stick to the gallery shortcode.
When used with Gutenberg Photonic creates no shortcodes, rather it creates blocks. If some of your posts were written with Gutenberg and some without, Photonic supports both scenarios.