Tools like Canva or Adobe Express allow you to put images on different pages/slides and export the entire project as a GIF.
The GIF format is limited to 256 colors. Avoid gradients or high-detail cinematic shots if you want to prevent "dithering" or graininess.
Available for both iOS and Android, the GIPHY app allows you to record directly through a "GIF Camera" that applies filters and stickers in real-time.