You need either Ethernet or good enterprise-grade AP(s). It's unlikely a mesh system will work (might need tuning), and forget trying to use the ISP's router-AP combo unless you're willing to sit directly within line-of-sight of it.
The hard requirement on Ethernet or good Wi-Fi is likely to exclude a lot of casual gamers, and those who do fit the requirements are likely to be enthusiasts who most likely do have a gaming PC already.