Sounds possible, but haven't found anything that's affordable or that looks legit that can achieve this in ($10-$50 range)
Basically, I have an isolated coax cable that goes from my office to the cable coax splitter in the master room closest where also my wifi router/switch is camping in. I'm not using the cable for anything, and I much rather NOT use wifi or those ethernet via power line adapters. (I'm a bit of a stickler with security, I know…)
But if there truly isn't something as such or two expensive, I may as well find a router in bridge mode support, and crank up the security to max.
P.S encase you are wondering, most parts of the house has wired Ethernet, except for the office room, and I use the wifi for guests or my phone.