This combination is really finicky with NiMH batteries. You’re only looking at 4.8v fully charged, and they don’t last long at all before it shuts down. And they pretty much don’t work at all with NiMH which aren’t in perfect condition and fresh off the charger.
The TPS62172 capable of functioning up to 17v input, but the Moto:bit schematic limits this to 11v - I presume because of the input capacitor, as everything else is on the downstream side. This is enough for an 8xAA battery pack provided they’re NiMH, and the additional voltage headroom should allow it to use the full range of the batteries before they fall off the cliff.
The legal department might have a stroke because someone could shove Alkalines in there and exceed 11v, even though it’s probably fine. But if you could squeeze a 12v input rating this thing really should have an 8xAA pack.