When you visit pm.prod.gce.gmonkey.us, you don't get a real website. Instead, you get a 404 error from a misconfigured server. The SSL certificate doesn't match the domain, so your browser will warn you not to proceed. This isn't a store, a service, or any kind of business — it looks like an internal staging environment that accidentally became public.
Legitimate companies make sure their public-facing domains work properly and have valid certificates, contact details, and a clear purpose. Here, there's nothing. The domain has no WHOIS records, no privacy policy, no social media presence, and no history in the Wayback Machine. There's simply no evidence that this site was ever meant for customers.
If you're wondering "is pm.prod.gce.gmonkey.us a scam?", the more accurate question is whether it's a real site at all. It's not. There's nothing to buy, log into, or interact with. The safest course is to ignore it — it's not a threat, but it's also not trustworthy.