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6) Why not just use SD-WAN
First, yes, when an edge device is behind the firewall, NAT or private LTE router, SD-WAN can be used to access that, it can be part of the SD-WAN just like any host or servers inside a VPN. This is in the IT domain of an enterprise. This assumes the enterprise has the SD-WAN network and also the IT department allows the edge devices to be part of the VPN in the company.
There are many different SD-WAN solutions, different enterprises use different solutions and they have different IT rules on the SD-WAN. How to use the SD-WAN software to access the edge device and applications for troubleshooting will be done case by case. The user can create an virtualized instance of the SD-WAN client as an App on the EVE device, the user's laptop has also to be part of the VPN. Setup the correct routing on the SD-WAN App, and the user can then access the other applications on the EVE device or the network connected to the EVE device.
Then, another solution can be to use the SD-WAN for EVE devices from the EVE controller independent of the enterprises. The EVE controller provider manages the SD-WAN controller and systems. The SD-WAN client runs as part of the EVE software. First of all, this needs to get enterprises IT permission to have a non-native SD-WAN into their remote locations, then to manage the SD-WAN controller itself, and make them scalable and HA is not a trivial task. There is also the challenge of security measures needed for managing multiple enterprises and synchronize the SD-WAN status to the EVE controllers.
While EdgeView solution is light weight, it does not need a controller for the operation. The EVE device controller needs to authorized and start the session, the rest of the operation is between the user and the EVE device using a private token which only has a limit life.
7) Why not just use WireGuard or OpenVPN
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