Series 1, 2, or 3 Apple watch Fall detection capabilities

I don't have an Apple watch nor do I know anything about them so my question is, are older series Apple watches capable of running fall detection Apps? I realize that they may not have heart monitoring capabilities like the newer ones but do they have accelerometer, gps, etc needed to run the fall detection apps that come with the newer watches or similar? All I know is that some may have GPS and others not?

I am wanting to get a fall detection device for an elderly relative but dont want to pay monthly subcrription fees associated with other devices dedicated to that purpose, especially if an older series $150 used apple watch is capable of doing the same job. Plus, if it looks better than a big plastic button around her neck She's more likely to have it on more often. She already has an iphone so I can easily just add it on to her existing plan. Thanks to all here, who take the time to offer their knowledge based opinions and help out us bondi blue imac gen-x'ers . -Mk