You can’t grant access on iOS “to view / edit / delete all/any data”, that’s physically not possible, even with the hidden SDKs that only select parties have access to.
It doesn't change the fact that tracking your detailed location and who you are around in combination can be used to determine your affiliations or sexual orientation. If you, with your secure iPhone, are located around numerous people with Grindr installed, they may jump to conclusions.
They are capable of targeting gays or political opponents with this, which is the point of the story.
I’m not aware of any government back door access, but carriers that I worked with had access to all sorts of crazy hidden SDKs within iOS. For transparency, last time I worked on those was 5-6 years ago, so things may have changed.
Something close to that, AFAIK. But then, it’s not “go download this app from the store”. More like “we steal your phone, jailbreak it, and now we can see everything”. Not sustainable at scale.