When it comes to quarterback, I've learned to look at three things: physical tools, instincts and football character. Things like footwork and release are lower on the list for me. They can be taught IF (and this is a big if) there is natural twitch in the feet and arm.
Physical tools are self-explanatory. The more you can do, the better you can be. The best quarterbacks have some special traits.
Instincts are critical and separate from learned skills. Anthony Richardson had elite physical tools, but he had no instincts. The clearest tell that Richardson lacked instincts was his running. He was never a great runner in college or high school. Compare that to someone like Jalen Hurts who dominated with his legs.
The last one is basic. You need your quarterback to have good football character- works on his game, plays tough, keeps his head on the field.
When you look at the best quarterbacks in the world, they always checked these boxes. Many of them had major questions coming out- Josh Allen was inaccurate, Pat Mahomes made wild decisions, Lamar Jackson was raw as a passer. But they got better with time and coaching.
Arch has more pedigree but falls in a similar bucket. He's a big athlete with an arm who needs technical work. I like his mental toughness and I think his pocket navigation and running ability reflect his natural instincts. As he continues to refine his game, I expect him to make leaps.