Does anyone know if it would even be possible to have a Panda update itself from an SD card it had access to? I’m wondering if it would be possible to get a .bin file or whatever it needs on the SD card and then get the bootloader to use that. I’m guessing the bootloader can’t use an SD card so it would need to come over the COM port from another device doing an XMODEM upload or something? Anyone have any reference material they could point me towards to do something like this?
Yes, only GHI products can do that 
Look for “in field update” in the GHI library