Here is an example material we recently added to textures.com. 3.25x3.25 meters! We are now able to scan much larger surfaces, up to 4 meter in height :) Of course the resolution is stil there, 20.000x20.000px for the final material.
https://www.textures.com/library
There is a lot more of these coming, we have a large queue of these massive materials waiting to be polished and published.
credits: photographed by our fantastic scanning team and processed into this material by me.
Pretty time-lapse