The app is, and has always been, "Wallet". The cancelled app was a peer payment thing to compete with Venmo, it wasn't about payment handling. Nor was it about NFC payment device handling, which hasn't changed either.
I distinctly remember adding it to the Google Pay app at some point in the past.
Checking my phone now, I see that i don't have Google Wallet, and instead there is an unbranded Wallet that may be on my phone? Just, what the actual F? Are those the same thing? If Wallet is a generic thing on my phone, do I want Google Wallet, which Google Pay is telling me I should be using to manage my credit cards, now?
As mentioned, there are multiple ways to access payment processing. Most people don't go to an app on their phone, they do it at the point of sale, likely by following a link from Drive or YouTube or TV or whatever to the web UI (pay.google.com in fact redirects to wallet.google.com).
But the core secrets management and NFC handling app on your phone is and has been "Wallet", and the fact that you claim to be confused about that now is just evidence that you've never needed to use this UI because it Just Works.
The nonsense in this thread is about this "GPay" app, which is not and never was a payments management app. It was a peer payment service, itself based on Wallet. And no one was ever confused about it until they needed an excuse to yell on HN. They just didn't use it much, I guess, so it's been cancelled.
The confusion is because "Android Wallet" was renamed to "Google Pay" quite a few years back, and only last year was renamed back to "Google Wallet". GPay was a separate app, yes, but it also linked directly into "Google Pay" for card management.
It certainly has not "always been" Wallet. First there was Android Pay, then Google Pay, then Wallet. This doesn't include their weird little market-specific side quests which included Google Wallet (a different app to the aforementioned Google Wallet), Google Pay Send, Tez and Google Pay (different to the aforementioned Google Pay, the one this article is about).