As the title says, does anyone know how can I reduce Unity project zip size, so it isnt very heavy? Most of my exports have been of +600MB, and I keep seeing awesome games with zip files lower than 50MB. Or what specifically do you make the zip out of?, so it isnt very heavy. Like, the whole project? Or just certain parts?

Maybe try 7zip and select the option of ultra compression it can compress the files by 4-50%

When zipping you only need assets, packages, user settings & project settings. The rest Unity will take care of when they load the project

I downloaded a 600 MB project file that had 20 HDRI skyboxes in it, but was only using one. I deleted the 19 others, and suddenly the project was over 5x smaller.

Moral of the story: don't include unused textures/sounds the space can add up quickly