Leaker reveals which Pixels are vulnerable to Cellebrite phone hacking

They couldn't answer the question most on my mind: "We’ve reached out to Google to inquire about why a custom ROM created by volunteers is more resistant to industrial phone hacking than the official Pixel OS. We’ll update this article if Google has anything to say."

Is grapheheOS actually harder to hack or does cellebrite just not put a lot of effort into supporting it because the very low odds of LEs running into one in the wild?

All of the listed features significantly raise the bar for exploitation ;

https://grapheneos.org/features

So Graphene is actually more secure than most stock ROMs, but e.g. banking apps won't run on it "for security"?

Why can't the stock ROMs use these features and be more secure also?