Sure, but those tend to be much more expensive, so depending on the actual cost of electricity in your area, it may take a long time for you to break even.
However, if you want to have a really small appliance-like pc, then yeah, the NUC-sized ones are much better.
The low-power AMD based systems everyone recommended a couple years ago were indeed great, until the ebay resellers realized what was going on and started slapping "opnsense pfsense AES-NI" etc on their listings and doubled their prices. The systems went from selling at $40-50 to over $100.
Also, the AMD processor in those systems is getting extremely long in the tooth.
However, if you want to have a really small appliance-like pc, then yeah, the NUC-sized ones are much better.