Here are some results I get. I have 3 linksys ea8500 routers running openwrt placed in different locations in my house so I can get full house wifi coverage. Tried downloading files from my NAS using phones/pcs I can max out the gigabit connection (about 100-110MB/s), so If switch can't hit this number the bottleneck is with switch itself.
Downloading nsp games from my NAS:
V1 unpatched switch 5g wifi: 10-15MB/s
OLED 5g wifi: 20-25MB/s
OLED with ethernet: 40-50MB/s
So obviously ethernet is the fastest option.
As for streaming, sysdvr has been out for quite some time, check it out if you mean streaming switch games on your pc. Or you can try chiaki if you want to stream ps4 games on your switch, and switch-remote-play/skynx if you want to stream pc games on switch.