It is possible because they hired the original author of Bun to do this.

It won't be possible to HIRE anyone doing this job confidently, they won't even know if they f*ked up.

I am not too worried anyway, one person with no context, with or without AI, can't do this job. Just like with all the AIs you have, giving you 10 millions, you still can't build a AAA game, it is that simple.