For reference, it’s been there since macOS 12. You may also like to know that this year (macOS 15) they added jq.

Unfortunately, it's not actually very useful, as whatever server they're using on the other end is severely constrained. networkQuality gives me:

Downlink: 884.856 Mbps, 198 RPM - Uplink: 13.238 Mbps, 198 RPM

whereas speedtest (whether to the official speedtest server OR a friend's home server in their basement!) gives ~700 Mbps uplink.