I ONLY mentioned the "more compressed" version cuz you said : "Perhaps they want a more compress version."
That post was only intented as a joke. Or if someone want to gift me an
unreasonable fast AMD* based workstation this could perhaps change my decision**, but honestly compressing a game should be done by the dev. I know Runey doing it already otherwise we would have 10 times the size of what we currently have.
But to minimised the size, you can do it the best if you have unrestricted access to all the source files. Even then they are some limits.
You can do much more, if you create the files with this as goal rather than try afterwards. E.g. the use of layers and to divided a image into back and foreground save space and this is something that can't be done afterwards. Or to used videofiles instead of "playing" still image for a video.
Disclaimer I only looked at the image files folder and do have little knowledge of the actual Ren'py engine and how easy/good this could be implemented with the restrictions of the engine.
*e.g. Threadripper Pro 3995WX or two socket Epic 7662 and up with 256+ GB RAM
**you can try, I would be pleased to have an
unreasonable fast AMD based workstation, but I give it a maximum chance of 10% that I would actually do it