bluetooth_classic

bluetooth classic demo
pico w, flutter android app, btstack

youtube demo

modified flutter main.dart to use dropdownbutton and maps
number to pico w mac address, I use linux bluetoothctl scan
to find the individual pico w mac address then I use a 
felt tip pen to mark the unique number on the metal 
shield of the pico w, the number on the metal shield maps to a
longer mac address of the pico w, see flutter modified file and
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