I am would be stepping the voltage up from 3v to 5v for steady input. I am apologize about the thread but it is still relevant to adapting AAAs as power input to microcontrollers, isn’t it? But it is a different type of XIAO, I am sure others will need to learn that too, that they work much differently than the others in the series.
I am still figuring out the LED schematic, I am going to use an arduino schematic plan, basically 3 leads in, VIN/GND and D1.