I think I’m right at our level on this… I’ve only done basic research into software. I think it is clear that if it needs to be Open Source, Autoware is the best you will find for this specific task, driving on roads and paths outdoors. Tesla and Google can do better but they are not sharing their source code.
I think the biggest common beginner mistake is to look at a big package like Autoware and say “This is too complex, I can’t understand it, so I will re-implement it all myself and improve it at the same time.” OK, it would take 500 man-years of engineering effort and you would not live long enough. But in only a month or two you could come up to speed with Autoware basic use. My platform was a ride-on kiddie car with 80Kg payload. Enough for a big computer. Then I got into walking robots.
Basic ROS nav is very primitive and uses SLAM which means running in a very controlled environment and not paying much attention to user road users. Outdoors, THE problem is predicting the future actions of others.