I ordered a Xyber NAS (N150) back when they were still in stock, wiped the Ubuntu that came with it and built up a NixOS config [1]. The power usage is very good (12W with 2 internal SSDs, bluetooth, wifi and a bunch of services running).

If it dies, I won't be too sad since it was about $210. But it's doing pretty well (24/7) so far.

[1]: This ended up being useful. The built-in eMMC chip that I had installed the OS on gave out after ~1 month of usage and I had to reinstall. Thanks to the NixOS config, it took me much less time.

Where most of these machines suffer is the default UEFI config and the cooling. The UGREEN luckily gives the option to dig into the advanced UEFI settings (they just left the entire setup open in "engineering" mode so every option the firmware gives is there to tweak) and optimize what the manufacturer defaults, change the power saving options, turbo and power limits, etc. This makes a huge difference.

But the CPU cooling is still sub-par and there's no off the shelf replacement. Most of these smaller Chinese NAS brands I tried have this issue, they take very decent hardware and slap on them the crappiest accessories like cooling. You get a hobbled CPU, always pegged at low clocks because the temperature spiked to 99C. Sometimes the disk cooling isn't too well conceived either and the disks bake at 45C idle but these can usually be compensated if you're willing to take the noise.