It's why I decided to make my current router a full PC running Linux with a couple of NICs and am looking into getting wireless working directly on it.
I’m wondering whether a mini-PC can route even 1 Gbps at line rate. Lots of people are using mini-PCs as routers, but most of them have only 1×1Gbps Ethernet interface and no PCI slots. The Minisforum DMAF5 has 2×1Gbps Ethernet interfaces, but that’s an off-label use and I haven’t seen any benchmarks.
Of course, if you go all the way up to mini-ITX, then there are plenty of options for various performances of CPUs and network interfaces.
Most mini-PCs are using 2-GHz-or-lower Gemini Lake CPUs with much worse single-core performance, but much better video I/O performance. But that still doesn’t cover network I/O, and Realtek vs Intel. (And Intel i40 vs i211.)
Relatively few people have gigabit Internet, but it can happen suddenly. 3 years ago, I upgraded from 20 Mbps DSL to 1 Gbps symmetric fiber. Bye-bye to my old MIPS 24K router. But all these years later, my brother 1 mile away is still waiting.
Sure you can half the power draw again with an embedded device, but diminishing marginal gain.
This is, unfortunately, pretty hard to do well. 5 GHz AP support is particularly complicated, as the AP is required to take some special steps to avoid interfering with other services using the band, including weather radar. Most consumer cards don't implement these steps, limiting them to operating as a client on those frequencies.
I'm not throwing out my Asus access point yet.
I’m not sure what the device manufacturers are doing to prevent unauthorized use of DFS channels, but I have a cheap router with a QCA9887 (GL.iNet GL-AR750) and it doesn’t use DFS channels no matter what firmware you put on it.