you can definitely use flyio-debug header for sprites 
nixie:~$ curl https://meow2-ibym.sprites.app -H flyio-debug:doit -I
HTTP/2 501
content-length: 357
content-type: text/html;charset=utf-8
date: Wed, 01 Apr 2026 12:41:37 GMT
server: Fly/dea3e0cdc (2026-03-30)
sprite-version: v0.0.1-rc31
via: 2 fly.io, 2 fly.io
fly-request-id: 01KN4H0JF51HQC9MCYWM23BMMH-ams
flyio-debug: {"n":"edge-cf-ams1-7a5c","nr":"ams","ra":"redacted","rf":"Verbatim","sr":"fra","sdc":"fra2","sid":"2861632bee55e8","st":0,"nrtt":0,"bn":null,"mhn":"worker-cf-fra2-2373","mrtt":6}
in this case my closest region is ams and my sprite machine is in fra.