Right. The question is whether that is a permanent limitation, or if they might open it up more broadly in the future. The diagrams in the write up show that it's a global caching proxy, so not very different from Cloudflare.
If you use GCP, you're using this system.
Google cloud CDN maybe, but it isn't clear if you can front arbitrary (non gce) sites with it. Or it if includes the ddos mitigation.