Who Me Too'd this solution

If you have no STB's and aren't using the coax for MoCA LAN, then you can absolutely run a pair of bridges between the ONT and your router's WAN port.   I did this for the longest time to get from the basement where the Ethernet terminated and my home office where I had my own router.   Only difference being that I connected the coax in a manner that made the run between locations point to point.