I could be wrong, but I would assume that it's likely because either
a) the size of the images/video are reduced significantly due to not needing 1080p quality by the devs
, or
b) the packaging and publication process does this part automatically.
If I remember correctly, the max file size for a Ren'py apk is 2GB (the only way around this is to have the rest of the game content download from a webserver at runtime, which I believe is actually against the F95 game upload rules), so my personal guess is that the devs probably did a lot of work to cut down the file sizes in order to fit the Android version limits.