If the apps sandboxed, how can installing an app cause breaches? As far as I know, iOS apps are sandboxed.
Either the sandbox is very weak and Apple instead relies on App Store audits, or they disallow users installing apps outside the app store to protect their 30% tax that makes them a LOT of money.
the malicious app, even signed off the app store could also exploit unpublished vulnerabilities to gain elevated access and not require asking for permission. even or especially if it's not a full sandbox escape.
Either the sandbox is very weak and Apple instead relies on App Store audits, or they disallow users installing apps outside the app store to protect their 30% tax that makes them a LOT of money.