It is certainly much easier to buy the cheapest router than to configure IPs manually if you are perhaps a layman yourself. I don't know what motivates you to do without a router. If it's the radiation, then the antenna can be deactivated on practically all wi-fi routers. If it is a missing port because everything is already occupied on the router, which you may already have, and you are using a secondary LAN slot on the mainboard, then it is easier to buy a small LAN switch and expand the router. (Works with any router)

I use Steam Link via a powerline connection to my gaming PC. And that without any problems. But of course some kind of router is needed for DHCP assignment. (Or IPs are configured manually)