Already tried Winrar, 7zip says error I think something is wrong with the .PAK cause it says Part 1 there should be a Part 1 but don't know were it is.
Many games have their own extractor. Unless you know exactly what program made it, AND you can find the proper extractor, AND you have all the files (if split) you're out of luck.
Yes I do own PS2 games I'm thinking of ripping all the SFX and sound effects so I can use them in some of he video's I make. I have over 100 PS2 games and lots of storage around 8 TB each one is 4 TB of space so 2 HD 😀