Mikrotik
Nekotopia works with affordable MikroTik routers running RouterOS v7. These compact devices support WireGuard natively and provide a dedicated WAN and LAN port configuration for connecting your home server or vintage machine to the torus. Here are some widely available options:
Mikrotik hAP lite (RB941-2nD) - ~$25, USB-powered 32MB RAM - WireGuard will run, but it's tight. Add a few firewall rules and you're sweating. 650MHz single-core. The absolute cheapest "I just want to put my 486 running a gopher server on the torus" use case, it would work. Powers off a 5V USB so you could run it from a phone charger.
MikroTik hEX lite (RB750r2) ~$40 USD The entry point. Five 100Mbps Ethernet ports, 850MHz single-core CPU, and 64MB RAM in a palm-sized plastic case. It won't win any speed records, but for sharing a low-traffic retro site or BBS, it's more than enough.
MikroTik hEX (RB750Gr3) ~$60 USD The sweet spot. Five Gigabit Ethernet ports, dual-core 880MHz CPU, 256MB RAM, USB port, and microSD slot. Handles WireGuard with ease and has headroom for firewall rules and traffic shaping. IPsec hardware acceleration.
MikroTik hEX S (RB760iGS) ~$79 USD Everything the hEX has, plus an SFP port and PoE output on port 5. Same dual-core 880MHz CPU and 256MB RAM. The SFP cage lets you connect fiber directly if your ISP provides it, and the PoE output can power a small access point or camera.