Unfortunately supply is quite limited. If you want to horizontally scale on these instances you need to have a good relationship with AWS so they'll give you a big allocation before c9i is a thing.
I haven't personally tried, so I can't say for certain, but Lambda has publicly stated they run on bare metal EC2 instances, presumably the supply of whatever instance types they use should be fairly healthy
The interesting part to me is less the exact hardware generation and more the control plane around placement, isolation, and startup latency. That is hard to copy outside AWS.
