XD does not have an Excel import, but:
- If you've created graphics in Excel try exporting them as PNG or JPEG and importing them into XD.
- You should be able to copy and paste text from Excel into XD (but you'll probably have to restyle it).
- If you want to make a working prototype in XD, you'll have to manually build the links.
In the future, you could build your site map directly in XD instead of building it in Excel first. To be honest this is the first time I've heard of someone using Excel to build a site map.
For previewing on the iPhone, on this page How to download and use Adobe XD on mobile to preview designs and prototypes Adobe says: Does Real-time Preview via USB work on Windows 10?
No. But we're working on Real-time Preview via WiFi for XD on Windows 10. In the meantime, please place your XD Documents created on Windows 10 in your Creative Cloud Files folder on desktop, and load them from XD on mobile.