So, in fact, this thread is just an exercise in rhetoric, and the emulation is impressive, but partial?
I don't think you get it?
I think we do. You're not emulating a VIC-20 at all because no real VIC-20 software will run on it.
Most people here thinks that the TVout library is an achievement.
Yes, but it's not really surprising or magical. It's really just a case of counting clock cycles very carefully.
If you want to make something that people will use then write a library that turns a pro mini into a display adapter with a few external resistors (or something like that). Send text to it over the serial port and it displays it.
Even so, the TV set is dying. I can get full color TFT screens on eBay
for about $6. Which would you rather have for debug output?
PS: The reason for emulating an Atari VCS would be that you get all the fun of counting clock cycles for an emulator plus you get to play the games afterwards.