Could I use it to power my iPhone? Frankly I’m fed up with the need for charging.
There's not a miniature nuclear reactor in there, it's just a RTG, which is simple but also very inefficient. So it doesn't get the crazy amount of power from a tiny amount of material a fission reactor does.
I believe these are not RTGs (radioisotope thermoelectric generators.) Rather they use radiovoltaic conversion, probably alphavoltaic conversion judging by the use of Pu-238. Such devices convert alpha or beta radiation directly to electricity using semiconductors, not unlike photovoltaic cells.
But your point still holds, these atomic batteries produce a tiny amount of power.
Maybe it would make people put phones in the sun all the time and wear out batteries with heat.
No, it wouldn't. Sunlight is ~1 kW per m^2. A medium-sized room has maybe a couple 60 watt bulbs, spread over 10+ m^2, each of which radiates ~10 watts of actual light.
Light indoors is pretty easily 1000x less than outdoors. Eyes work exceptionally well in low light conditions, so we don't even realize the enormous difference in brightness.
If it's on for 8hrs a day and you capture all of it, on 1/5000th of a room, you get... 4mWh, or in reality, 0.7mWh because panels aren't perfect?
You could make a call in a few months of charge time. with a 3x3inch panel. But yeah, I suppose I was wrong and "eventually" is a bit of an understatement.
However I do not trust the public to dispose of recyclable waste properly, let alone radioactive devices.