You can maximize > 1gbps bandwidth by wiring your devices with at least 2.5 gbps NIC card (i.e., PC) back to the 2.5 gbps port of your XB7 in modem/router mode. To expand the ports, you can buy at least a 2.5 gbps unmanaged switch, plug it to the lone 2.5 gbps port, and then plug your PC to the new switch. That’s the cheapest way.
Your Netgear router only has 1gbps ports, so to use them, you can plug it directly to one of the XB7’s gigabit ports, and make sure it’s in Access Point mode. Plugging it to the 2.5 gbps port of the switch or the XB7 doesn’t gain you anything beyond 1 gbps.