Here's the single PCB version of the LoRa motion detector:
It works as expected. The entire board is roughly the size footprint as the 3x AA batteries that are a part of it. Thanks to @NCA78, it's using an XC6206 LDO.
I just received a 3D printer kit today. I suppose the next step will be to print a 3D case for it. Ideally I'd like to make it waterproof/moistureproof so that it can also work outdoors.