If you want to be very secure, host a VPN and don’t open any ports besides the VPN port. Then access anything as though you’re on LAN.
Use it to make a webcam server. You could probably afford to plug in multiple webcams since it has USB 3. Great for checking on the home when you’re away.
Make it into a router and access point. Connect your phone to the AP and use tcpdump to capture packets from your phone for a few minutes. Look through the packets with Wireshark and see how much data is being leaked.
What is their reasoning?
Would you offer Dynamic DNS like www.duckdns.org?
Is it safe to host a public server on your home network? I’d feel safer if it was on a VPS just in case it’s compromised.
In a distant post-apocalyptic future, the survivors will use hard drive platters as a currency.