@mmip, I have an Intel i7 NUC that is always on. It runs my unifi controller software, FTP server and a syslog server. This PC is a client of my ZeroTier network and is always connected to it and receives a ZeroTier IP address. This machine has a local IP of 192.168.1.13, but it’s ZeroTier IP address is something like 172.x.y.z. When you set up your ZeroTier network, make it private and you must authorise devices to connect to your network. ZeroTier is free for up to 50 clients (if I recall correctly)
When I am at work, my laptop VPN client is blocked by the corporate network, so I connect my laptop to my ZeroTier network, this is a secure connection. I then run VNC on the laptop and connect to the ZeroTier IP address of my PC at home over the secure ZeroTier network. I am now remotely connected to the PC. I then open Internet Explorer on the remote PC and enter the IP address of a camera and I have access to its GUI. This is the only time I use ZeroTier -when my OpenVPN client is blocked by a corporate network such as at work or when I am overseas and the hotel's network prevents VPN traffic going out. I have used ZeroTier when I was in western Cambodia to view my cameras back at home in Australia. It works quite well.
When I am on cellular, I just activate OpenVPN on my phone and connect remotely to my always on PC To view my cameras. This means you have to have the OpenVPN App on your phone and the OpenVPN profile certificate needs to be copied onto the phone as well. This is covered in this site pivpn.io. When I connect to the VPN via my phone, I can access my cameras using the DMSS app which allows me to see my camera live feeds.
When you add devices to your ZeroTier network, they all get a unique IP address for that network. I have two RaspberryPi, that are also clients to my ZerToier network. This means I can connnect directly to them from my laptop when the laptop is connected to ZeroTier. I have a NAS that is also a ZeroTier client and connected as well. There are instructions on ZeroTier website for setting up your network.
if you get a Raspberry Pi, you can also put PiHole on it and use it a LAN wide ad blocker (in combination with browser ad blockers). I have two Raspberry Pi running PiHole on each as my two DNS servers. One of them runs the OpenVPN server, the other one runs the WireGuard VPN server.