Gifcurry
Gifcurry is an open-source video editor for creating GIFs, built with Haskell and works on Linux, Mac, and most likely Windows[1]. It has both a graphical user interface (GUI) and a command-line interface.
With Gifcurry, you can edit GIFs or videos by cropping, trimming, seeking, adding text with custom fonts, altering duration, changing size, setting frames per second (FPS), tweaking color count, enabling dithering, importing subtitles, and saving the output as either a GIF or video[1].
To run Gifcurry, your machine needs to have GTK+, GStreamer, FFmpeg, and ImageMagick installed[1]. Linux users can download the AppImage, prebuilt binaries, or install it via pacman (Arch) or snap[1]. Mac users can follow the instructions on the readme page, and eventually, there will be a Homebrew formula for easy installation[1]. Gifcurry hasn't been tested on Windows yet, but it should work if you know how to build Haskell programs[1].
Citations: [1] https://lettier.github.io/gifcurry/ [2] https://github.com/lettier/gifcurry/releases [3] https://github.com/lettier/gifcurry [4] https://appimage.github.io/Gifcurry/ [5] https://github.com/lettier/gifcurry/blob/master/Gifcurry.cabal