Break it into multiple devices. Get a router upstream and then get a switch and some APs. If you can't run cables look into mesh.
For WiFi 6 devices look here: https://openwrt.org/toh/views/toh_available_16128_ax-wifi
To be honest with you wifi 6 doesn't offer that big of leap from WiFi 5. It is a little faster but devices need to support it.