A router you can flash with a modern OpenWRT is likely a good option. Check the project website and/or forums and/or reddit for recent recommendations. That's what I did in the past.

Personally I've moved to OpnSense: Some run it natively on a refurbished low-power SFF hardware (6000 or 7000 series Intel should be fine, or some Ryzen), so even in countries with high electricity costs that's feasible these days.

More specifically, I run OpnSense in a qemu/libvirt VM (2C of a E5-2690v4) and do WiFi with a popular prosumer APs. Mind that VMs are likely to introduce latency, so if you try this route, make sure to PCIe-passthrough your network devices to the VM - I was prepared to ditch the VM for a dedicated SFF.