Can we find all the proxies list using a particular shared flow in ApigeeX?
Yes, but you need to rely on "brute force" , basically:
The good news is, there is an external tool, apigee-scanner, that can do this kind of scan for you.
Example
node ./scanProxies.js --token $TOKEN --apigeex --org $ORG --latestrevision --sharedflowuse sharedflow-name
It does other scans too, and is easy to extend.
Good luck.