Linking everything with Telegram might be a good idea. Since you cannot have 10 different Telegram accounts. This might restrict it a bit further
Believe it or not, some sockpuppetters has more than 10 Telegram accounts. They probably used online number or something like that to generate their account, or simply create their own bot to do that.
Don't do airdrops based on social media accounts! Make airdrop based on holding some other asset at given time.
Someone can have multiple wallet address, I think it might not prevent cheaters if they have a lot of money.
The only think that I know so far even though it is not popular is KYC, it is very hard to have more than one ID from your government even though somebody might simply steal it from other person (but this is very risky to do).