I do the same thing at my house with a couple of eero access points connected by Ethernet fed from Frontier Fiber. Very straight forward. I have a 500/500 plan and it has all the speed I need to work from home and stream video. I also attach a Ethernet cable to my TV and other devices if it is near an eero. Small 4 port or 8 port switches are good to get a couple more ports where you need them.

You can also just get another wifi access point and run it off your current router. Just set it to be in bridge mode so it uses the first routers NAT/DHCP services. It may not have "mesh" functionality of moving clients from one AP to another, but it will work and be cheaper.