I doubt this would be as effective as a sprinkler because sprinklers cool surfaces as well as extinguishing. But I could see it being a useful complement to a sprinkler, as a first-line defense in the early moments of a fire starting. Sprinklers only kick in once the fire is already well-established and do enormous water damage.

Yeah, that was my thought too.

Additionally, even if they cannot replace sprinklers, not all buildings even have sprinklers. This technology could still be useful for cheap retrofits to add some fire protection at low cost rather than either demolishing or performing an expensive sprinkler.

It could be useful in places that can't use sprinklers like clean rooms and maybe data centres, as a first defence before they activate the super expensive & human-killing gas suppression systems.