Video editing

I do not know of a good open source movie editing software tool.

Imovie is a good free alternative for Mac/iPhone/iPad users.

And Davinci Resolve is market leaders of movie editors and free for Windows and Mac

Further, Final Cut X is my preferred tool.

iMovie (Mac)

iMovie (iPad iPhone)

DaVINCI Resolve 16 (Windows & Mac)

Final Cut Pro X (Mac)