Eneloops are life. That's all I use. My cheap hands immediately drop lithium primaries the moment they touch them. If a single use over the lifespan of the cell is more than like two cents, I cannot bring myself to buy them, let alone use them. I've got two L91s someone gave me, and I have not used them. They are for "emergency use," in a scenario where I've drained my few dozen Eneloops, haha.
I'm okay with a more basic programming. Otherwise, it gets into something like Anduril...I'm currently waiting on a D3AA to try that UI out, again, haha.
It's interesting, because I assume Li-ion support was dropped in favor of the circuit just running things dead under a certain voltage. But then also, it's not like they're SUPER efficient on an Eneloop, so I can't see how a boost/buck would be too big of an issue, unless it's a physical space concern in the head.