Make animated GIF from a movie created in iMovie.app on Mac
You can do it using the Keynote app which is preinstalled on every Mac:

Create a basic Keynote project
Remove all unnecessary text elements from the first slide
Drag and drop your video from the Finder into your first slide
If needed, edit Document's size to the required size of the final gif image
If needed, trim video in Format-&gt;Movie tab
Export Using File-&gt;Export to-&gt;Animated Gif

Here is the detailed instruction: https://macmost.com/create-an-animated-gif-from-video-on-a-mac.html