Download Ladik's MPQ Editor and use it to open War2Dat.mpq from your Good Old Games Warcraft 2 Battle.net Edition installation folder
Download JCField's listfile
In the MPQ Editor, click on "Add Listfile" and select the file you downloaded
You will find .grp files in the "Art" folder which you can extract
Change the spritesheet columns and rows dropdowns before loading a .grp file.
Browse to a .grp file and all the frames of the .grp will be loaded as individual sprites.
Click a sprite to add it to the spritesheet.
Hold alt while clicking a sprite to add it to the spritesheet flipped horizontally. Needed for the SW, W, NW images.
A "Save as PNG" button will appear to allow you to save the spritesheet.
I then opened the .png files with Photopea and resaved them because the browser doesn't save them with palettes so this lowers the file size.
Spritesheet columns:
Spritesheet rows:
Sprites:
Spritesheet: