I'm suggesting to use material (physical) definition here for avoiding vagueness

A worthy goal. But does that work? When philosophers "build up the definition from most basic known physical model", does that really reduce vagueness? Particularly in a field like cognition where there don't yet exist any good (i.e. not speculative) physical models?

My experience is that this reductionist move does not help. If it has any effect at all, it provides a pseudo-dissolution of the question - leading to someone reframing the question in an even more indirect and mysterious form - one which is more resistant to being dissolved.

I'm myself by now (or “for now”) a proponent of phenomenological ontology, not a materialistic one; but please ignore if you are not sure what it is.

Sounds promising. I'm myself an anti-realist; but please ignore because I am not really sure what that is.