A while ago, Yifan Lu, a member of PS Vita hacking group Team Molecule, posted a technical blog on his website, explaining how he attempted an HDMI mod for the OLED PS Vita and why it didn't end up as successful as he hoped it would be. He also explains the truth about the OLED's "mystery port", whether the Vita has any video output capabilities as well as other interesting discoveries. You can read the whole thing here.
https://gbatemp.net/threads/yifan-lu...mi-mod.497510/
https://gbatemp.net/threads/yifan-lu...mi-mod.497510/