Honestly the latency to ANY real world service would be sufficient. They could nominate a dozen .gov websites and it could be ISP’s choice which one they test a

Honestly the latency to ANY real world service would be sufficient. They could nominate a dozen .gov websites and it could be ISP’s choice which one they test against. If they can have a fast ping to nasa.gov, then the infrastructure is capable of fast pings. Bandwidth tests already deal with the ways ISPs might play games with upstream capacity.