I guess someone should present the 3rd (bit lazy) option:
If you build up a library of gifs and have them stored on your device anyway, just open a file-browser and drag-and-drop the gif/picture into the editor at the place you want it.
This
can sometimes be iffy and make the editor insert it twice, usually then one full size and a thumbnail version, and as it can't be seen which is which just delet both and you'll still have the original picture below the editor to choose to insert as full image or thumbnail.
Nice and easy
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Drag and drop can work from other pages too, but i found it messes up too often so i usually download gifs i find worthy.