If you’d like to reduce the network latency further you can store each trie node as a file, naming it conveniently the prefix path to that node. Then dump the few hundred million files onto R2.
Now the traversal can be done completely via CDN lookups!
Cloudflare R2 doesn't distribute files globally. They only cache requested files in PoPs. So then it would function the same as an API behind the Cloudflare CDN.