Perhaps the problem is how we model sentience. Perhaps the default should be everything is sentient but limited to the interface that exists as boundary conditions.

To say otherwise is almost the path to sure error, and many terrible historic events have happened in that vicinity of categorization what is and isn't.

Perhaps we should go by what sentience means. To feel. A being that feels. To feel is to respond to a vibration in some way. That is to say, anything that has a signal is sentient in some way.