This is a collection of all the official environments. I'm aware that this was made before, but I think all of them are outdated by now, so this one will be updated with every new map. Also I include the SFM maps.
If there is a mistake, please let me know, I worked with a lot of files and it's easy to make a mistake.
-.vmf of all the maps environments
-.vmt and .vtf of every skybox
-A list with all the skyboxes and the maps that uses it
-Instructions on how to use it