There have been plenty. For example, the CANDU series of reactors developed in the 1950s and 60s. Breeder reactors were quite popular during the early days of nuclear power, as it was initially thought that there was maybe only 100 years’ worth of (easily accessible) nuclear material on earth, rather than the thousands (or tens of thousands) of years’ worth we know of now, due to both more reserves being discovered and also easier methods of fuel enrichment being developed. The fact that breeder reactors have fallen out of favour due to abundant fuel reserves certainly says something.

Breeder reactors produce more fissile material than they consume.

Not many people know the history of the treaty. It basically was signed under duress. Prior to the meeting where it was signed all but one of the Maori tribal leaders were against signing the treaty, even the Maori version. What was said at the signing was purposely never recorded, but considering the existential threat of the New Zealand Company (NZC) on the horizon (the primary reason a treaty was even being discussed), it is believed that the Maori leaders were basically given the choice of ‘sign this treaty and be a part of the British empire, or don’t and have no legal rights against the whims of the New Zealand Company’.

The New Zealand Company was a private British company with the goal of obtaining as much land as possible at any cost, and the Maori would have had zero legal protections unless they were part of the British empire. Without a treaty the NZC would have been able to push out the Maori entirely with no repercussions. The British people who brought the treaty to the Maori leaders knew this was coming, and wanted to avoid it.

Signing the treaty was a quick and dirty solution to the quickly approaching NZC and was responsible for preventing the worst of the damage, but it is a very flawed document. The translations were rushed, and vague. Basically everyone was against signing it, but they knew it was the least worst option available. It was never designed to be the core document underpinning a nation, merely a speed bump to stall the private annexation of New Zealand.

The MSP430 is just the chip I happen to use at work, if you’re not convinced you could try looking for an actual ultra low power chip, I found the STM32U0 at 70uA/MHz and the STM32U5 at 16uA/MHz in the first result.

Even ignoring selecting a more efficient micro, a smattering of tiny ceramic caps will buy you a few hundred microjoules for bursts. If you’re already operating at 2V you can get a 6V rated 100uF cap in a 1210 package - and that’s after considering the capacitance drop with DC biasing. Each one of those would buy you 200 microjoules, even just one ought to be plenty to wake up for a few tens of milliseconds every second to get a reading from some onboard peripheral (as an example) then go to sleep again.

For sure, you’re not going to be doing any heavy lifting and external peripherals could be tricky, but there are certainly embedded sensor use cases where this could be sufficient.

It’s more than you think. I work with the MSP430 microcontroller, which is capable of a sleep current of 40nA @ 2V, full active mode at 140uA/MHz with all onboard peripherals turned on. With this you could achieve almost a 20% on-off ratio with a 1MHz clock, or keep it in active mode all the time at ~150kHz, which is sufficient for many embedded sensor applications.