GIMP
- Prepare all layers, the bottom one will be the first frame
- Select filters>animation>Optimize(for GIF)
- ExportAs yourfilename.gif
- Turn on Animated Gif Optons
- Set delay to 2000 milliseconds (2 seconds)
- Set “Use delay entered above for all frames”
https://neondigitalarts.com/how-to-make-a-gif-using-gimp-software/
Photoshop
- Prepare all layers, the top one will be the first frame
- open the Timeline panel
- On the right panel’s menu, select Make Frames From Layers
- Set the loop option on the bottom Timeline panel to Forever
- Set each frame duration
- Export as a gif File > Export > Save for Web (Legacy).
https://www.adobe.com/creativecloud/photography/discover/make-a-gif.html