I would go with Davinci Resolve (free edition), which has one specific feature useful in this case, a waveform. https://duckduckgo.com/?q=davinci+resolve+waveform&t=h_&ia=videos
You could use the "general" waveform.
the luminance of the images must be the same as the faces in the test condition.
I do not know how strict this condition must be, ...
All pro or advanced hobbyist level video editors have what you need. If you already are Adobe CC customer, the extra cost is mostly the time needed to learn one of its video editors. You can compose views, match colors, sizes and luminance levels plus add blur effect with standard functions.
The technique is quite basic: select the photos, place them to the ...
When I used After Effects it was only saving me 2mb. So I made the clip in Prem Pro then used https://ezgif.com/optimize to compress it and it went down from 22mb to 4.5mb.
I'm sure there's a better way to do it but saved me installing and learning a new programme