It is anycast that I'm going after. Requirement for unmetered bandwidth (or cheaper than AWS et al) is because of the kind of workloads (TURN relays, proxy, tunnels etc) we'd deal with gets expensive, otherwise. For another related workload, per-request pricing gets expensive, again, due to the nature of the workload (to the tune 100k requests per user per month).

So far, for the former (TURN relays etc), I've found using AWS Global Accelerator and/or GCP's GLB to be the easiest way to do anycast but the bandwidth is slightly on the expensive side. Fly.io matches the pricing in terms of network bandwidth (as promised on the website), so that's a positive but GCP/AWS have a wider footprint. Cloudflare's Magic Transit is another potential solution, but requires an enterprise plan and one needs to bring-your-own-anycast-IP and origin-servers.

For the latter (latency-sensitive workload with ~100k+ reqs / month), Cloudflare Workers (200+ locations minus China) are a great fit though would get expensive once we hit a certain scale. Plus, they're limited to L7 HTTP reqs, only. Whilst, I believe, fly.io can do L4.