“Created in collaboration with Telegram, Gram Wallet is powered by the core engine behind My Wallet…”
Interestingly, this line is not present in the App Store description, where only the My Wallet engine and Telegram-exclusive features are mentioned.
Also worth noting: alongside the long-standing wallet.ton.org domain, a new walletgram.org domain was registered just a few weeks ago and is now being used for app.walletgram.org. (docs.ton.org)