For completeness, there is one other approach: instead of VPN'ing in to each location, you can add a 'VMS plugin' to each location, and have the video data stream to the cloud. This way you'd have a centralized view to all of your camera feeds in one browser-based viewport, at the speed of cloud, instead of having to depend on how good the connection to the remote location is.
In addition to the centralized view, you'd also get video backup and/or archival, and cloud-run analytics (so cheaper and faster than on-prem solutions).
If you don't know how to set up and configure a reputable VPN product -- correctly -- then I would strongly recommend not doing it at all. An incorrectly-configured VPN can be an extremely easy entry-point into a customer network and a potential vector for a breach.
The world of remote access / VPNs is not something that beginners should be attempting to tackle. A few bucks now for such a service could turn into a breach with major repercussions for both the integrator and the client down the road.