Verification scam on Telegram

I received an official looking message on Telegram that said I need to go through a verification process to confirm that I'm human. I did so on my iPhone. Soon after I realized it could have been a phishing attack and searched online. There are clearly many mentions of this scam occurring. Based on my reading of some articles, I looked for linked devices and found a new session established from Singapore. I deleted that session. A few minutes later I deleted by Telegram account and removed the app from my phone.

Now my question is: other than mirroring my telegram chat messages to this other device in Singapore, what else could the scammers have done? I'm not worried about the messages since I rarely used the app and don't have anything useful or important in my messages. Could the scammers have injected malware into my iPhone (like keylogger, etc.) and steal information, data, etc., from all my interactions with my phone? Or was the attack surface restricted to the Telegram app?

In addition, a lot of people talk about how these scams are used to drain the victim's wallets. Which wallets are they talking about? How does the scammer get access to other wallets/apps on the device (specifically the iPhone)?