Easy way to buy/store crypto for US expats?

I'm a US expat living in Viet Nam, looking to buy crypto to pay for poker coaching.

I don't plan on having more than a hundred dollars worth at a time, so security isn't a big issue. What I care more about is convenience in terms of setting up the account, and buying/storing transferring the crypto. Hopefully I can do it all from the same app.

I've spent the evening looking into binance, kucoin and coinbase. Binace and kucoin don't accept US citizens, coinbase does but won't allow access from Vietnam.

Any other ideas?