This mirrors my anecdata on consumer (<$150) wifi router hardware. I recently upgraded my home router specifically for wireguard and it's been 5x faster than openvpn.

My laptop can run chacha20 at 2GB/s on a single core. Encryption performance hasnt really been an issue for a long time. Most VPNs will be running AES128 that has hardware support and should be even faster.

In addition to been faster it is also the only vpn that reliably handle roaming, without interrupting active connections.

Used 10GbE ethernet components are cheap on ebay.

I built a 10GbE 'switch' by buying 2 4 port SPI+ PCIE cards off of Ebay and then joining them together with a conventional Linux Br0 bridge on a old Intel gaming machine. Had no problem keeping up with line speed.

I didn't test wireguard with it, but it should work pretty effectively for testing what speed it can get up to.