Steemit Wallet and Bittrex/ Poloniex Question??

Hello all,

I wanted to see if anyone knew how you can buy/ sell STEEM and/ or SBD. through the steemit wallet. STEEM seems to go through Poloniex and SBD goes through Bittrex. Neither option seems to be available for the US.

How are user's getting around this issue using the wallet?

thanks so much.