Sure. There's always a downside to everything. OP wanted a solution for small donations, and Nano is still the best option. It's worth it to take on some volatility risk so that the people donating know that all their donation goes directly to you, and anyone in the world can donate any amount with or without a bank account, just by showing a short address on your site's page.
And no, it's not at all like an airport currency exchange. In that case there's a deliberate actor trying to defraud you. Volatility is a property of all assets. Some have far more than others. Just understand that and you'll be fine.