You can achieve what you want using your public IP adress, even if it's dynamic. First, you need to config a port forwarding in your router. To do this, enter in your router settings, go to port forwarding and there add the LOCAL IP adress from your XAMPP computer. Make sure to select type TCP and RANGE 80-80, because port 80 it's the default port for apache. Make sure you don't use Skype, which also use port 80.
After you did that, reset your router so the changes apply. Now, go to https-vhost.conf file and add something like this
<VirtualHost *:80>
#ServerAdmin webmaster@dummy-host.example.com
DocumentRoot "path to your wordpress directory"
ServerName your public IP
ServerAlias your public IP
</VirtualHost>
After that, go to hosts
windows file (System32/Drivers/etc/
) and add your IP twice. So, it should look something like this:
localhost localhost
YOUR PUBLIC IP YOUR PUBLIC IP
Don't forget to replace YOUR PUBLIC IP and path to your wordpress directory. Now, restart your apache service. I recommend you to perform a clean wordpress instalation in your wordpress directory and use YOUR PUBLIC IP for the website URL.
Briefly, this is all about it. I'm here if you have questions or problems!