Join intro, content and outro

more reference aand this

ffmpeg -i intro.mp4 -i content.mp4.mp4 -i outro.mp4 -filter_complex ^
"[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] ^
concat=n=3:v=1:a=1 [v] [a]" -map "[v]" -map "[a]" concatOutput.mp4

1. Video form one Audio file and one image

https://superuser.com/questions/1041816/combine-one-image-one-audio-file-to-make-one-video-using-ffmpeg
ffmpeg -y -i imag.jpg -i audio.mp3 -c:a copy result.mp4

2. Video from multiple images to loop for an audio file

https://stackoverflow.com/a/71837127/14984674

It's more efficient to do this in two steps.

1

ffmpeg -framerate 1/5 -i Scan-130802-%04d.jpg -vf "scale=1920:1080,setsar=1" -r 5 -c:v libx264 -crf 25 -preset slow scan-video.mp4

2

ffmpeg -stream_loop -1 -i scan-video.mp4 -i "1.mp3" -codec copy -shortest -fflags +shortest -max_interleave_delta 200M video.mp4