@YasuTiger
Hi,
You won't be able to install some third-party antivirus software on a Windows 10 ARM-based PC. However, Windows Security will help keep you safe for the supported lifetime of your Windows 10 device.
For your reference:
Surface Pro X app compatibility
https://learn.microsoft.com/en-us/surface/surface-pro-arm-app-performance
Since Surface Pro X has its own anti-virus called Windows Defender, if you are not doing anything risky on the web, you should be fine with the built in, make sure smart screen is on.
Hope above information can help you.
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