Are there examples of this being used on large outdoor spaces?
Yes, Waymo did the whole San Francisco block: https://waymo.com/research/block-nerf/
Woah, this video is way more interesting than the Nvidia polaroid teaser in the original link.
Still, NVIDIA's achievement (and Thomas Müller in particular) is amazing. Thomas and his collaborators achieved an almost 1000x performance improvement, by a combination of algorithmical and implementation tricks.
I highly recommend trying this at home:
https://nvlabs.github.io/instant-ngp/
https://github.com/NVlabs/instant-ngp
Very straightforward and gives better insight into what NeRF is than any shiny marketing demo.