Benchmarks at Comparative Throughput Testing Including NAT, SQM, WireGuard, and OpenVPN
I think the whole ath9k vs. ath10k, open-source-based, debate is about "religion", not about performance or reliability.
At 33 Mbps, aggregate, any MIPS-based device with a clock speed over ~500 MHz, from a reputable manufacturer, should be sufficient for routing, NAT, and SQM. (As would any current, ARM-based all-in-one.)
For gaming, as noted, lag spikes can be deadly. A multi-core device can help mitigate this, if budget and availability permit.