The only option is to paste each frame onto Images-to-GIF maker. You can theoretically get a GIF longer than 20 seconds at 60 FPS.
The problem is that you have to paste every single frame onto the Images-to-GIF maker, and if you want 60 FPS GIFs, you are going to spend a while doing this. And there's a file size limit of 4 MB that prohibits you from destroying Imgflip's poor servers. This means you have to be careful.