Another thing I can say is that, the site the scammer suggested had an option to connect your wallet. It could be that all of these are just big excuses to get you to connect your wallet to their site. And the moment it gets connected they plan to drain your wallet. Of course this is only a theory.
I know this doesn’t change the fact that this is a scam, but I just want to clarify that the option you are referring to is not for connecting your wallet but it’s for connecting your Telegram account. You login into the website by linking your telegram account.
Another thing I found when reading their faq is that selling your tg username dosn’t involve handing its credentials to the buyer, you are just selling it as an NFT.
This is making me more curious to figure out what’s the catch here, tbh!
I guess the scam will happen at the payment phase where you will likely be asked to make a deposit to be able to withdraw the paument.