My goal with this intro is to make something hand-solderable though, which is why I'm using QFP32, 0805, etc. In addition, this is Arduino Nano compatible to ease the transition. I'm using a CH340N for USB. An unfortunate consequence of this is that you need another MCU board to flash the bootloader first.
TBH ATmega328Ps are surprisingly expensive ($2.x) for their functionality.
Especially with the smartwatch, we are considering using an ESP32 WROOM/MINI module and will write about that too, eventually.