Yeah, but you would need to run an API server in each of those to reach that latency, and even then you're well into eventually-consistent distributed system headache if you accept the POST without synchronising with all the others first.

You terminate SSL (err, TLS) at the pop so the clients TCP connection gets setup faster, and then you use a hot TCP connection from the pop to a centralized API server. That gets you not having to deal with the headache of running a distributed system but a better experience for the client.

And you still have to send your light pulses through a fiber over thousands of kilometers, so 50ms is still physically impossible.

If you want 50ms then you're gonna have to do the distributed systems headache that rcxdude was trying to avoid. For everything smaller than Google, that's too expensive, but it can be done.