I bring my dog nearly everywhere I go. But he's a very quiet dog and it would be easy to forget he's with me in the back seat. I've lost sleep a few nights where I've had nightmares that I forgot he was with me and left him in the parked the car on a hot day. A week ago, it finally happened that I forgot he was back there and went inside the house only to realize 45 min later I didn't know where he was. Fortunately, it was a cool evening after sunset, so no harm was done. I have a whole process I typically follow to make sure I don't forget (but I didn't follow properly the time I left him in the car). I would (literally) sleep better at night if the car monitored for the presence of a pet (or a child), alerted the driver via the mobile app and automatically enabled pet mode.

I'm not sure what all of the sensors are that could be leveraged here, but have a few ideas. At a minimum, the car does seem to have weight sensors in the seats for the seat belt alert system, so those could a starting point. There also seems to be some sort of camera or motion sensor near the rear-view mirror that's pointed at the driver's area. I'm not sure how sensitive the suspension travel sensors are, but if they're relatively sensitive they might be usable to detect such motion.