There are other ARM solutions:
(https://www.youtube.com/watch?v=QNH7jBgs14c)
(https://www.youtube.com/watch?v=xhZBHLmGO5Q)
(https://www.youtube.com/watch?v=UMbTibi3n2k)
You will have to wait till late 2028 (titan lake) for x86 to come close and it will likely be expensive.
PICO-ARU4-A10-0004 – Core Ultra 7 255U, 32 GB LPDDR5 – $1,155
PICO-ARU4-A10-0003 – Core Ultra 5 225U, 32 GB LPDDR5 – $988
PICO-ARU4-A10-0002 – Core Ultra 5 225U, 16 GB LPDDR5 – $887
What does it mean "idle"? Permanent gigabit would be 1W, no chance to down-rate aka EEE. 1W HDMI port. Get your specs in line with reality.
you’re kinda ice skating up hill when you could just buy a Rockchip rk3588 based device, though maybe you are doing some kind of guerilla marketing 
EDIT: ahh I see you’re using a raspberry pi 4, well there you go
Yeah, I’m promoting overpriced old RPi4 with ethernet and storage barely dangling on USB and crap idle consumption, even made a photo of this shameful act. Where can I get my check?
Of these three R6C is the only one with M.2 NVMe support.
It seems it can idle sub-1W with a proper NVMe SSD and one 1Gbit EEE port up, which is kind of impressive.
Not sure about quality and longevity of upstream support for Rockchip ARM though.
That sounds 'unlikely', if you consider that either of those will inevitably cross the 1 watt limit, without even thinking about the SOC underneath.
There should be a +1 for funny
Now shall I trust some random dude on german forums who shared his extremely detailed and technical power consumption tests, or another random dude on openwrt forums who posted "unlikely”…
From Samsung SSD 970 EVO Plus datasheet: Power Consumption Idle L1.2 mode 5 mW
From Intel Ethernet I219 product brief: With EEE, Intel has reduced the idle power of the gigabit link from about 500 mW to just over 50 mW
But please don’t let these facts confuse you.
These days, three years is a minimum a serious commercial-grade hardware maker would wait before putting a new embedded processor in one of their products. A lot of people got burned when the AVR54 defect was discovered...
Right now, the only commercial-grade device sporting an N100-adjacent processor I know of is Caswell CAD-0124:
https://www.cas-well.com/products/network-security-management/desktop-appliance/cad-0124/
The rest are still on the fence about the whole N100 thing.
"2 x 2.5GE RJ45 Ports (Intel i226-V)"
I bet they all loved getting burned by intel 2.5G.
Yeah, I’m promoting overpriced old RPi4 with ethernet and storage barely dangling on USB and crap idle consumption, even made a photo of this shameful act. Where can I get my check?
Arrest him! 
haha.
Maybe you could find an older mini pc / dev board based on something like the Atom z8350, these were the ‘trail’ socs instead of the ‘well’ or ‘lake’ socs. They are built more like arm boards/phones with components being lower power but then you also get that hit or miss style support and the i/o will have greater limitations I assume. Just goggling around I see there were ones made with mini-pcie slots so you could run an ethernet port off that and then perhaps the only trade off you’d be making is EMMC / usb instead of NVME. I assume it will route 1g but looking at https://github.com/cyyself/wg-bench I’m not sure it will handle 1g of wireguard, it lists a z8530 example there and I assume with advancements the speed is better than listed but needing almost double is maybe a stretch ?
For the record, such devices do exist here in Japan. I have a Venusense UTM-50E-J (aka Restec DS-UTM-R1) hanging out in my network, according to a Tapo plug's measurement it happily idles at 3 watts. I'm not using it as an edge router, and Its Celeron N2807 is not a powerhouse, but I believe it could just about handle routing a gigabit line.
Is the cabinet metal? If so, you can just buy some paste. Is the cabinet metal? If so, you can simply buy thermal paste and the cabinet will act as a heat sink. It's very possible to dissipate the heat from the N150 after undervolting.
You can use copper pipes to transfer heat. (not brass, copper)
Ancient atom x5-z8350 plus usb gig card idlle’s @3W , without 2.5 or something on dc side. My box is some mini pc with 12V power supply adapter connecter to powerbank . dell/wyse have thin client on this soc wyse 3040 or something and it’s powered from 5v so it’s possible to run it from stronger usb port.