Connect a controller via USB and select > Update from USB/PC . 💻 Guide: Using with Vita3K (Emulator)
The official filename will be exactly: PSVUPDAT.PUP (all caps, one 'p' in "update"). Psvupdat.pup Download
Psvupdat.pup is a system update file for the PlayStation TV (also known as the PlayStation Vita TV). Connect a controller via USB and select > Update from USB/PC