If you are updating official firmware:
If your Vita can't connect to Wi-Fi, you can update it via a PC or USB drive. Emulator Setup: Modern emulators like Psvupdat.pup Download
If you search for "Psvupdat.pup download" on Google or Bing, the top results are often third-party "file repositories," forum posts, or shady download aggregators. If you are updating official firmware: If your