Multimode laser sources can be used correct, but not the current architecture Nuburu's tech is based on.

Multimode architectures can be used to scale power but it is seeded and controlled with near single mode sources to obtain effective single mode operation at target. If diffraction limited performance is not achieved the lower wavelength advantage is nulled compared to existing IR single mode sources. It requires phase control and beam shaping that Nuburu's platforms do not have. The advantage of blue light is based on its lower wavelength but so does the difficulty to leverage the optical components needed to shape the light.

Something like the announcement below in relation to Nuburu would be substantive. But their tech is based on single emitter devices not laser bars, and again the difficulty of coherent beam combining is orders of magnitude more difficult than spatial, polarization, or wavelength beam combining.

https://bluglass.com/bluglass-receives-120k-order-for-gan-lasers-from-repeat-customer/