Can I use Fast Gallery for Gutenberg with existing images in my media library?

Yes, you can absolutely use your existing media library images. Fast Gallery for Gutenberg integrates directly with the WordPress media library, so you can select any uploaded image when building a gallery block.

You simply add a new Fast Gallery block in the Gutenberg editor, then click to choose images from your media library — no re-uploading needed. The plugin does not automatically convert existing embedded images into galleries; you'll need to manually create new gallery blocks and select the images you want to display.