To get Grand Theft Auto III working on your PS Vita, you need to use a homebrew port (such as the re3 engine port). Since the .vpk file is just the application launcher, it will not work without the original PC game data files. Prerequisites
If your screen goes black or returns an error after clicking the bubble, check these common fixes: gta 3 vpk ps vita work
Let’s cut to the chase: How well does it run? To get Grand Theft Auto III working on
In general, while it's technically possible to get GTA 3 running on a PS Vita through unofficial means, the experience may vary widely depending on the specifics of the port or hack used. Legality: Downloading games in VPK format for PS
Performance: The game is stable, with the option to overclock the Vita to 444 MHz or 500 MHz for even better performance.