Hawker and peddler are used sometimes, but street-seller in probably more common these days.
Street-seller is probably the most neutral.
Hawkers and peddlers may be stationary, or may travel. When I was a child people would sometimes walk up the street hawking their wares. (selling their goods/things). French onion sellers were a common sight, peddling their wares from their bicycles. Sadly, they don't do it nowadays. I miss them.
So, for people selling from a fixed position, street seller, or street vendor, is probably best.