the people employed in the mural-painting industry are not quaking in their boots over the prospect of this device automating their jobs away.

Note they do not print billboards on site. The approach those folks use might be adaptable to needs like this, possibly they're already explored the commercial opportunities there and "large format vinyl printing" is already a service one might find commonly offered.

It's good that the taxpayers are funding research like this. Otherwise it has to be done by silly geeks and artists as hobbyist experiments / stunts.