They do work, and any exercise is better than none... as long as you're not injuring yourself! For someone who has rarely to never done resistance training 1x a week over 6 months will make a massive difference.
I'd also put it out there that the best thing you can do, especially as an older male, is simply squats and deadlifts. IMO they stress the body in ways most other lifts do not.
IMO, any male over 40 should be doing resistance training, yoga and cardio at least once a week.
Yes, my point is do resistance training properly. Someone who has never done training as in your example should do so only under supervision. Squats and deadlifts are great but both novice and experts for different reasons injure themselves with those two. Fyi, audiophile bill squats over 200kg and deadlifts way more. Ask him about injuries and training.
The problem with all these toys is that it gives people the false impression they are exercising, when they should be actually exercising properly. those who say any exercise is better than nine invariably ends up doing one day a week. If you are good at exercise and have been doing it for years, great. If you are not, spend on a trainer in a proper gym.