I bought a small USB-powered router a few years ago in the form of the NetAidKit and it's the computer that I've been carrying around with me the longest. Originally it was recommended to me by people that had made their Thinkpads ethernet-only to avoid malicious firmware blobs. I got one because I was running Genode on my Thinkpad in the days before the Sculpt distro and the driver at the time didn't support my wifi card, but ethernet worked fine.
The device I have is a GL.iNet 6416 branded as the NetAidKit and came with firmware that included a Tor node and proxy, but at some point it started running stock OpenWRT.
At the moment my home is only networked with a wifi link to the neighbor's house. Rather than put wifi hardware in my desktop I setup the little router as a wifi client in the window and connect over long ethernet (I picked this trick up while squating). To take one step further I've run USB power over blue and brown pairs in a Cat-6 cable (same pairs as PoE) and stuck it in a microwavable food container up on the roof.
The ethernet cable I found in a dumpster at the university. The USB cable was what was within reach. I didn't realize it until I cut it open that it didn't have an data wires, but that made things easier.
I ended up with RJ45 connectors with open ends. The crimper wasn't designed for this but it made it possible to omit the other wires at the jack.
I soldered the USB jacks in and covered them with heat-shrink insulation.
The router fits in plastic food container. The cable hole is not sealed but the bulge of electrical tapes fills the gap and retains the cable.
The other end of the USB cable goes on other side of the cable. In retrospect both plugs should be the same length from the split.
The cable goes out the window and to the roof, and the housing is zip-tied to the old UHF antenna mast.
