There have been many debates about this lately. I believe completion percentage is a key indicator of accuracy and even a sole indicator when looking at a whole game, season or career. Let me explain why I feel this way.
It is true that completion percentage alone isn't the single measurement for accuracy. On-target percentages and catchable percentages are used too.
The numbers below are average numbers across multiple seasons and don't account for any kind of distance.
Russell Wilson - 65% completions, 73% on-target, 79% catchable
Teddy Bridgewater - 67% completions, 74% on-target, 79% catchable
Baker Mayfield - 61% completions, 70% on-target, 76% catchable
Patrick Mahomes - 66% completions, 72% on-target, 78% catchable
What is the trend here? Do you see a pattern? While we don't have this information on Pyne it's reasonable to expect that in order for Pyne to complete 70% of his passes he would need to throw a higher percentage of on-target balls and even higher percentage of catchable balls.
Another source link
https://www.sisdatahub.com/players/5048
Link: https://www.sharpfootballanalysis.com/analysis/quarterback-accuracy-expected-on-target-percentage-baker-mayfield-russell-wilson/