It absolutely depends on your definition of consciousness. Every conversation about a concept depends on the definition of that concept. My definition is based upon sensation, processing, and decision-making, in regards to the self and the environment. I’d argue that plants and even cells exhibit simple forms of consciousness. If you take the emergent-property perspective, I’d argue even molecules and individual particles have a broad and abstract consciousness, although certainly several orders of magnitude less sophisticated than yours or mine.

The statement “we have only ever observed that in a very specific set of complex systems which is brains and possibly fungi” tells me less about consciousness than it does about our ability to observe it.