Hello
For upgrading machine from windows 10 to windows 11, you can choose the option "Keep personal files and apps" to help save data, but for the sake of double security, it is recommended that you back up your important data first to prevent unknown issue during the upgrade.
Yes, TPM 2.0 is a hardware requirement for windows 11 so it need to be enabled. Generally if your app is compatible with windows 11, it works after the upgrade, but as Norton Security is a 3rd party app, it is suggested to check if there is any notifications from the Norton website. Also it is suggested to backup the important files before perform upgrade.
How to Get Windows 11 for Your Compatible PC | Microsoft
Best Regards,
Wesley Li
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