Alternative if the first one doesn’t tickle your fancy.
https://github.com/cavi-au/Consent-O-Matic

I recently found jtx board.
It has journal, todo list, and notes functions but it can be customized to only show whichever function you use on the main screen.

As far as i know, for pillow to do what you want you would need to

• Take a gif and split it in to frames
• Edit each frame individually
• Put frames back together as a gif
• Repeat for every gif
  
  It can be done automagically like you want, but if you’re not interested in learning python maybe the XnConvert or ffmpeg comment above might be the way to go for ease of use.

I used python for everybody when i first learned python. I found it helpful to learn the basics. It’s free as a pdf so you can check it out. And then it can be bought as a book or for kindle if you desire.