Found it very interesting!
Apparently there is not a lot of ethernet controllers supporting IEEE 1588, apart from BCM54210 found in CM4 I’ve looked up two Realtek ones: RTL8211FG and RTL8125BG. They’re present in some mesh wifi stations and couple of desktop motherboards, I wonder how is PTP support there in mainline kernel for that.
p.s. Ironic that Jeff talks and endorses open-source hardware and solutions whilst being a big Raspberry Pi advocate. RPI is infamous for being full of binary blobs and with ARM cores there being 2nd class citizen essentially (with proprietary GPU being “the alpha”).