Couple of problems here. So let’s say you use one of the chips running at 25 uA (lowest run mode). First of all the does not include any peripherals. UART/i2c/timer/adc/dac don’t run in that example. And god forbid you want to do RF!
Then we also need to allocate power to rest of the board. The power supply is going to have quiescent (30uA if not more… probably more as it’s probably a HV source). Then you need to allocate power to sensors and rest of board, and the uA go fast.
Yes that's what I mean that you have to take great care, I was trying to say that it's not easy to engineer around these, just feasible. You still want some capacitor buffer, work in short bursts, sleep everything aggressively, etc. And while there are definitely useful applications they aren't gonna be as revolutionary as the headlines that always come up about these things seem to imply. But you can do more than power a few gates.
Regarding power supply, I'm not sure what these exact ones are, but other betavoltaic batteries are not high voltage. They're in the range of a volt or two and these are probably the same since these work more or less the same way as every other betavoltaic battery with a bit of extra proprietary sauce.
Edit: Also regarding RF, you can do passive RF via backscatter or a complementary RF energy harvester. Imagine a temperature sensor that logs data a few times a day powered off the battery, and someone with a handheld scanner comes by and reads it out every so often. Or an active tamper seal that spends most of its life making sure a wire isn't broken. Just brainstorming, but something like an RFID tag that can do stuff while it's not being interrogated is the main proposed use I've seen for these.
