Google, along with everyone else, still uses ASIC-based networking hardware from the traditional vendors where they need the bandwidth. But full marks to their PR department for the idea they have it all solved themselves.

They're definitely using miracom lanai chips for part of it at least; google engineers are the maintainers of the lanai llvm backend.

Seems odd that MS and G are the ones using special hardware, but only reach to 24 and 16 gbps respectively, while AWS hits 100 gbps networking. Is AWS already using specialized HW as well?

I'd guess the bespoke hw is not necessarily faster signaling, but rather functionality. E.g. fast multipath routing in a Clos fabric, firewalling, maybe offloading some specific workload (IIRC ms was using fpgas to offload some aspect of search for Bing)

Going back to signaling, AFAIU the state of the art is 25 Gb/s per lane, 100 Gb networking aggregates 4 of those. 50 Gb/s is still in the labs.

56Gbps serdes lanes are being used in network chips right now.