No.
Think of the VPN like a secure way of forwarding all traffic to your internal private network. Without the correct username, password, pre-shared key, x.509 certificate, etc, the VPN will NOT allow traffic into your network. If you supply the correct security credentials then you are able to securely stretch your little private home network out across the internet to encompass your smart phone as if it were at home and not at Starbucks or the Mall etc. Another way to think of it is it would be like having a really long network cable with one end plugged into your home network and the other end spooled up in the trunk of your car, as you drive around it unspools and remains connected to your home network. When you want to access your home network you open the trunk of your car and plug that cable into your phone and you are connected to your home network, this is in essence what a VPN accomplishes.
The only thing exposed to the open internet is the VPN. It could be argued that the VPN has "open ports" to the internet, which is does in the sense that the traffic from the internet must be able to reach the VPN server part of the Asus rt-ac88u. But there are NO ports passing from the open internet to your internal network or its devices such as the Hikvision nvr.
The greatest hits of how it would work:
1. Be outside of your home network, either away from your place physically or not connected to the wifi etc
2. Launch the VPN app on your smart phone (once the VPN app is configured to find your specific VPN) and connect it
3. Launch the app you use to view your cameras, use the same IP address you would use while at home for example 192.168.1.155 or 10.0.0.7, etc
4.
5. Profit