If you have an iPhone, you can get an Apple Watch and set it up using the other personβs phone. The health app will tell you what the personβs heart rate is. It will also do sleep tracking and check blood oxygen levels. It will also notify you if the person falls. It can also be used to contact 911 if it is in range of your phone, or if you buy the cellular version and add it to your cell phone plan.
If you live near an Apple store, stop in and ask about it. The trick will be to set up/link your spouses watch with your iPhone so you can continuously monitor the other person.