Most non-living agents have the ultimate goal of serving living systems. E.g., a thermostat has the proximate goal of stabilising temperature, but the ultimate goal of keeping humans warm.

I don't see in what possible sense you could say that thermostats have the goal (ultimate or otherwise) of keeping humans warm. I believe you will find that most of them will keep heating rooms with complete indifference whether humans are there or not. Honestly, depending on how narrowly you define "a thermostat", it's not clear that it even has the goal of stabilising temperature - it may well only have the goal of responding to certain inputs with certain outputs in a particular pattern (it will generate the output responses and be perfectly happy even if it's not attached to a heating system).