I’ll try to not be dismissive of the labour, though it’s kind of funny (or actually natural) that the heavy lifting libraries that only a few can actually write are open and free, while the shallow wrappers that everyone can write are paid and closed. Decades ago we were calling out these software and now it’s the norm. Another example along the line: I wanted to extract a frame from a video on iOS, it’s impossible w…
The authors and maintainers of foundational code/utilities like ffmpeg/curl/etc. should definitely be the ones who have all the riches they could ever want. Thousands have made fortunes off of their work. That said, what's the free and open source version of this tool? There are some great open source video editors like Shotcut, Openshot, KDENLive, Blender, etc., but I think this tool is more like CyberChef for video…
PowerToys is Free and Open Source, and has at minimum an image resizer utility. It's a good starting point for adding on richer functionality like a preview GUI, and I'm sure that the basic video and audio manipulation would be appreciated as additions. Also since it's a Microsoft sponsored project, I imagine that the signing process is drastically different than what OP has experienced.
I know that's really not satisfying to say that "someday we could have this in the FOSS space", but everything starts somewhere.
Though editors like Shotcut and KDENLive are considered non linear since you can layer on different effects, while OP's utility is definitely not that.