I think this is intended to offer simultaneous dual-band (2.4GHz and 5GHz) using two separate radios, as all decent APs for over a decade have done. The SoC provides one of the two radios, and the second is connected over PCIe. Whether your 2.4GHz or 5GHz radio more badly needs an upgrade in a few years can be hard to predict.
I'm reasonably sure this line of chips is designed to be the only active radio in an access point:
> Filogic 830 packs a wide variety of features into a compact, ultra-low power 12nm SoC, allowing customers to design differentiated solutions for routers, access points and mesh systems. The SoC integrates four Arm Cortex-A53 processors operating at up to 2GHz per core for up to +18,000 DMIPs processing power, dual 4x4 Wi-Fi 6/6E for up to 6Gbps connectivity, two 2.5 Gigabit Ethernet interfaces and a host of peripheral interfaces. Filogic 830’s built-in hardware acceleration engines for Wi-Fi offloading and networking enable faster and more reliable connectivity. In addition, the chipset also supports MediaTek FastPath™ technology for low latency applications such as gaming and AR/VR.
My reading of that is that the ARMs are there for software defined networking tasks, and not to run the router OS. I could be wrong. However, the OpenWRT spec lists this chip as a network adapter, not as the main SoC.
I think the "Filogic 820" branding may actually apply to the combination of the MT7981B SoC and the MT7976C NIC. https://wikidevi.wi-cat.ru/MediaTek seems to have actual detailed specs for these chips. It looks like the MT7981B is what has the ARM Cortex-A53 cores to run Linux, Ethernet, PCIe, and a 2x3:2 radio. The MT7976C is just a NIC with no application processor cores, but it has both a 2.4GHz and 5/6GHz radio. A NIC with two separate radios seems to be a relatively recent development, probably spurred by increased demand for tri-band routers after the opening of the 6GHz band.
