Whether it's 1 Watt, 1000 Watts or 0.0001 Watts is utterly irrelevant. It's the activity that matters. Even at the power quoted in the article of 100 microwatts

Whether it's 1 Watt, 1000 Watts or 0.0001 Watts is utterly irrelevant. It's the activity that matters. Even at the power quoted in the article of 100 microwatts, you're still talking activities on the order of a full Curie, assuming 100% efficiency (betavoltaics are down in the 10s and 20s, realistically). Curie-quantities of activity in a package the size of coin is real activity, not the nanobananas of tritium in the pacific the media likes to segfault over. No nuclear regulator in their right mind, in any country on Earth, would generally license, let alone exempt, a Curie-level quantity of any isotope for widespread consumer usage. The title of the article was "A tiny radioactive battery could keep your future phone running for 50 years." I can assure you this will not be going in anybody's personal electronics. At best, it will power some board-level electronics operating in the Arctic or at the bottom of the ocean, maybe a cubesat or keep-alive circuit on a space probe. Militaries, government agencies and companies with the motivation and resources to deal with the licensing could definitely have a use case here. Your average Joe will remain stuck with smoke detectors, tritium keychains, polonium static brushes, and uranium rocks as the hottest isotopes they can (legally) get their hands on.