The built-in mics on the Zoom are a stereo pair and they give a much wider perspective on a scene than a shotgun. They should be able to get a decent recording, but it depends on the situation...if you are too distant all that width means you might get a recording of mostly ambient sound. You can always add wind and people chatting later as additional layers in your effects, but you can't take away those things once they're in your recording. Wind can sound awful in a zoom, and just one person loudly talking near the recorder can ruin a concert recording even for BG purposes. Basically if the sound you want is a particular street musician, try and get relatively close, get a good recording of that.
Related advice...make sure you have headphones for field monitoring with a tight seal on your head to passively isolate the noise as much as possible...otherwise it will be hard to tell what your zoom is picking up compared to what your ears are hearing in the environment.
Hope this is helpful advice...above all though, bring plenty of batteries, and probably extra SD cards! And don't try to fill your SD card to the absolute max, because they can occasionally become corrupted that way! Happy sound hunting.