I cannot connect to (specifically) google.com with any app using cellular data
This sounds like it may be an issue with your mobile service provider's DNS. I would try to Reset Network Settings to see if that clears out the cached DNS results.
To reset network settings: Tap SettingsGeneral > Reset > Reset Network Settings
Happened to my wife, and after trying a lot of things it looked like it was something to do with location services.
I went into settings, privacy, location, turned off location services, then turned it back on.