However, bottled alkaline water is just purified water with chemicals in it to make it alkaline. It does not contain any significant level of H2. And, of course, there is the environmental problem of single-use plastic waste with the bottles.
H2 is anti-oxidant, anti-inflammatory, upregulates production of our own anti-oxidants including glutathione and superoxide dismutase, and many other benefits. So the real benefit of these machines is the H2 - nice that it is alkaline, but H2 is the hero.