Are there ChatGPT equivalents that write entire apps in the works?

This would have to go in the very-far-off category right now. GitHub Copilot is your best bet but it can only write functions and help you finish your own code. (That is a huge help, though.)

To put together a full app requires a greater understanding of how software parts fit together with a backend and user interface. Language-based models like ChatGPT don't address that problem and aren't a route to solving it right now.