So you didn’t turn off the auto upgrade toggle in the settings? That’s a shame.
If you’re one of the lucky ones that haven’t updated yet, this is the first thing I would do.
Settings > Device Preferences > About > System Upgrade > turn off auto upgrade
The second thing you should do is:
Settings > Apps > see all apps > show system apps > System Upgrade > Force Stop and turn off notifications
If you already updated to Android 11 there are two things you can do.
Install the HotFix update. This will fix some of the issues, but not all. HotFix Image
Take your chances trying to rollback the update by flashing your device to a previous version. I’d only recommend this for more advanced users. And I will not be helping with troubleshooting if you do something wrong. Shield Rollback
You should know that these kinds of issues have occurred with other updates in the past. It doesn’t mean they won’t work on fixing all the known issues. So maybe just give it some time. I don’t think Nvidia would intentionally cripple a lot of the apps that made the device a popular alternative to the Amazon Firesticks. They just did a terrible job of rolling out this update. I have read that apps such as X-Plore should be uninstalled and reinstalled after the update and then you can go into the app permissions to change the settings. Then you should be able to access everything as you did before.