Is a replacement display flex cable available anywhere?

While a replacement flex cable is available, it’s very difficult to replace because it’s soldered on, right on top of a very sensitive display. Even a skilled microsoldering tech could damage the OLED panel. On top of that, it sounds like the device has liquid damage. So even if you do successfully replace the flex cable, the display may have already been damaged by the shorts caused by the corrosion. I would start by cleaning the corroded connectors with rubbing alcohol and a toothbrush.