Don't know where you can get one unfortunately. Have been meaning to create a device page for this thing. Don't known when that will happen. But let me put some info in this thread at least.
The Telenor "Wifi Ruter II" board is a ZyXEL EX5700-T0. This is part of their ISP offering, which I believe includes many more variants than the examples at https://service-provider.zyxel.com/emea/en/products/ethernet-cpe indicates. Model numbers are not necessarily useful in any case. These routers are always(?) made to customer spec.
The Telenor variant is extra weird. It has a Telenor designed case. And it runs non-ZyXEL firmware, including the bootloader. Which is why I decided to flag the supported device as "Telenor". It includes workarounds for a couple of bootloader features which probably aren't necessary with a ZyXEL bootloader. But hopefully not harmful.