I discovered that I don't need any video editor to make a static music video.
How? It's quite easy. I only tested it on Windows platform however.
You just need an FFMPEG binary. Place it in a folder somewhere.
And an audio file + image file (jpg etc), place it in the FFMpeg folder too..
Open CMD/Powershell, then navigate to the FFMPEG folder.
Pass the following command to CMD/Powershell:
ffmpeg -loop 1 -framerate 2 -i filename.jpg* -i filename.flac* -filter:v scale="trunc(oh*a/2)*2:RESOLUTION*" -c:v libx264 -preset medium -tune stillimage -crf 18 -c:a copy -shortest -movflags faststart output.mkv