Yeah I agree, but ptpv2 does support unicast and you can set offsets. It would be very challenging, but not impossible sans the very high res stuff where you need oscillators on the switches and routers, as you alluded to. It wouldn't get down to the sub-10 nanosecond sync you get with a proper stratum 1 timesource (such as the rubidium decay ones), but you could get faster than the guaranteed 1 second of accuracy which is what I believe ntp used to guarantee from a protocol level.
That was my point. Also if you're inside one of Cloudflare's many POPs, this could, in theory, be provided.
