That's bogus unless you're talking above 10G, in which case the only things typically doing wire level performance are expensive and sold by vendors like Cisco, Juniper or Arista (and maybe it's higher than 10G now). Frankly, the vast majority of ARM based routers, unless you go out of your way, are garbage. Any x86 built in the last 15+ years with a NIC that's also not trash _will_ push at least 1G routed with a non-trivial firewall on a modern Linux kernel no problem. I've still got half a dozen PC Engines APU2 boards that unequivocally will get right at 1G on Debian Trixie; newer ewaste like Dell Wyse thin clients or Optiplexes would absolutely smoke those boards on performance.

Setting up a router with Debian is really kind of overstated in terms of difficulty, and frankly half of everything wraps Debian anyways (looking at you Ubiquiti/Vyatta), so why learn someone else's half cooked configuration language when you can just do the real thing.