How many different biochemical schemes for life do you suppose the laws of physics support? It's probably a lot. But how many of those are successful enough t

How many different biochemical schemes for life do you suppose the laws of physics support? It's probably a lot. But how many of those are successful enough that we're likely to have found their implementations? I'm thinking it's far fewer. Mostly just because "successful" is a hell of a filter, but also because the ability to eat your competitor is a hell of a benefit--which would create a bias towards compatibility and away from schemes that have to regard the users of competing schemes as unusable matter. This is supposing that certain parts of the periodic table are more hospitable to biochemistry than others (i.e. that we don't have transition-metal-based life forms that just operate too slowly for us to notice, or some other orthogonal sort of way to be alive).