@nicolas-flam yes sure,
in the page builder click on the "+" button on the left side
click on Element > Images > and drop on your page a contained image element
double click on your image > click on Replace image > there you can upload your own GIF, before upload please be sure to uncheck the checkbox about the image optimizer, this is not compatible with GIF images
FYI unfortunately GIPHY API is currently down so you can't browser directly their content from our UI, but you can still upload your own GIFs manually as explained above