I liked listening to James Lovelock and played with computer models of the Gaia hypothesis back in the late 80s. It is a good example of ecology in many ways. Sentient in the same way that a ball rolling down a hill is sentient though. Also, no more a single living system than our cars are a single system. The engine does not feel when the wipers stop working. It is a huge conglomerate of separate pieces with their own function and we call it a car.

I wouldn't consider the planet a "God". However, the rest of the concept is appealing to me. But what's that make humans? A virus? A few folks I know think that the planet may be in a very early stage of pre-sentience, and that something developing from the World Wide Web might be considered a rudimentary "nerve system". All thought provoking ideas.

all life has evolved together to suit all environments and many have died out because they couldn't adjust just like we will soon. the planet won't care if it becomes another dead rock.

The earth will continue to exist long after us and might even evolve intelligence after humans have gone, but it is not and never will be "God". "God" is the creator, around from the beginning according to the majority of beliefs. It's absolute nonsense to try to fit this to be a new definition of God or any other deity, because it clearly couldn't create itself.