ChatGPT writes excellent API documentation and can also document snippets of code to explain what they do, it does 80% of the work for unit tests, it can fill in simple methods like getters/setters, initialize constructors, I've even had it write a script to perform some substantial code refactoring.
Use ChatGPT for grunt work and focus on the more advanced stuff yourself.
This is a kind of grunt work that years ago would have taken me hours and it's demoralizing work. Nowadays when I get stuff like this, it's just such a breeze.
As to copilot, I have not used it but I think it's powered by GPT4.