As for VGA i think you are out of luck, or need a faster/specialized co-processor. VGA requires 3 analog inputs of at least ~30MHz, and an ESP8266 has one analog input in the low (I think I've seen 20) kHz range, so more than 1000 times too slow.
You're welcome. I looked into it because it would make a pretty cool project and while pretty advanced, not impossible.
The cheapest analog-digital-converter chip I found is the TVP7002. Dealing with the digital pixel output is still way way too much data, but now it might be possible to scan the picture a few pixels each loop. The reasonable approach would be to process it in an FPGA or specialized chip and only deal with a compressed and scaled image in the ESP8266.
As for VGA i think you are out of luck, or need a faster/specialized co-processor. VGA requires 3 analog inputs of at least ~30MHz, and an ESP8266 has one analog input in the low (I think I've seen 20) kHz range, so more than 1000 times too slow.