try using Aptos (APT) network. For now, it's the cheapest network for transferring $USDT.
I do not recommend that Aptos (APT) does not yet have high adoption, whereas fees on blockchains like ERC20 and BNB are extremely low with just as low as $1 can execute more than 200 transactions. SOL offer more number of transactions.
Very unfortunate that move language based blockchain is having low adoption despite being fast and cheap, if they were more popular, they could dominate the stablecoin remittance niche.
If you're sending stablecoin, you should try using L2 like Base, they have huge adoption, almost every exchanges accept it, fast, and average fee is close to zero, the most recent USDC transfer on base that I saw only costs $0.0008 and could go even lower, definitely worth a try.
If you want to use USDT, simply use Plasma, it has zero fee USDT transfers and also as fast.