Well, it turns out that a Seeed Xiao esp32 lora board fits exactly into the 18650 battery bank case from the dollar store. Added a 2500Mah cell, and RAK PCB internal antenna. Getting 14hrs from full charge to the cutoff, Bluetooth connected the whole time. I'm sure a NRF52 would fit just fine as well.
Its a meshcore companion. The original battery bank PCB is gone, and the lora radio happens to be the same size, so it fits in its spot.
Thanks, I just looked at the pretty picture and not the community! ๐