There is a lot of choice in the <$150 range. You could get eight of these and a cheap 10-port switch for any kind of clustering lab you want to set up.
Here is an example: https://www.aliexpress.com/item/3256804328705784.html?spm=a2...
The successor product on the company's site uses a 12 volt, 2 amp power adapter: https://www.bee-link.net/products/t4-pro
Here is a YouTube review of the linked model with input power listed at 12 volt, 1.5 amp (link to timestamp of bottom of unit): https://youtu.be/56UA2Uto1ns?t=129
It's not really worth comparing further as the configuration are significantly different, but if your goal is doing 110MB/s R/W, even when accounting for power consumption the product in the article is much more expensive.
G4560 suggests you're not processing much, is the NAS caching a lot?
4G is probably enough. Though nextcloud does use a lot of memory for miniature generation.
As for the G4560, I can stream 1080p with jellyfin so it packs a surprising punch for it's power envelope.
Picked one up off craigslist for ~$50 and use it as a plex transcoder since it has QuickSync and can simultaneously transcode around 20 streams of 1080p content.
There's even people selling their souls to the devil for the ability to control the actual voltage of their chips, increasing performance per watt drawn!
But only Gods and top OSS contributors can control the power draw of chips integrated into drives/extension cards/etc
These are thin clients but flip an option in the bios and it's a regular pc.
Only downside is the limited 8gb storage, but it's enough for a minimal linux install with a couple containers. You just can't beat a regular x86 pc when it comes to just being able to install an up to date distro of choice.
What happened? I remember buying a Pi 3B+ in 2019 for less than 50€.