No qualifications to talk Microsoft. Still my two cents believing this is more about networking. (If your instructions from the year 2003 was valid, this should holt too.)
As you already stated, your project has three stages:
1. Moodle on 'localhost'
2. Acces in the LAN
3. Opening to the Internet
For stage 2 you change $CFG->wwwroot to 'http://private.ip/moodle', where private.ip is the IP your Windows 10 machine in the LAN, possibly 192.168.1.117 in your case. If another computer in the same LAN answers to http://private.ip/moodle, you were successful. Strictly speaking, you should now run the https://docs.moodle.org/en/Search_and_replace_tool to replace the old URL with the new one.
For stage 3, you need to change $CFG->wwwroot again, this time to 'http://public.ip/moodle, where public.ip is the "proper" IP address you got from your provider, your router might call it the WAN address. You need to configure your router to some kind of IP forwarding from the WAN IP to your Windows 10 LAN IP and NAT routing for the machine to reply to the calling IP. This is the tricky part. If you managed to give your WAN IP a domain name (in the DNS), you have to use that in $CFG->wwwroot to 'http://private.ip/moodle'. Once it works, the replace tool has to run again.
That said, there are other alternatives for test runs. MoodleCloud is free up to 50 users. My favourite is the MoodleBox https://moodlebox.net, a SD pre-installed with Moodle latest for Raspberry Pi 3 and 4.