Hubitat administration is local only. Want to Create A Rule.. it's local only. Want to to use the Rule, it's available worldwide via Dashboard. So... OpenVPN is MOST useful to gain Admin access. You don't want to hand your Hub over to the internet so that anyone can 'adjust your rules' - which port forwarding allows.!!
NoIP is a DNS tool. It's used to give a name to your ISP's assigned IP address for your home. It's usually a dynamic address, meaning it changes with reboot, yours or theirs. NoIP gets updated from your home, and thus when you are not at your home. you can find it's IP address.
That is the trivially easy part. OpenVPN has two parts, your router at home AND the devices you take with you when you're not at home: phones, tablets, ect.
You can find out if your home router (modem) has OpenVPN option with the make and model.
Using the Configuration menu of your home router, you'd enable NoIP and OpenVPN. Usually simple clicks and id/pw words. Then install the OpenVPN client app on your mobile device and again, follow the prompts to complete the setup.
Once it's setup you simply turn the VPN on, and 2 seconds later, when it says Connected, you use it.