Just like in the topic. Code below in CMakeLists.txt doesn't make BTstack to dump HCI comms:
target_compile_definitions(picow_bt_example_common INTERFACE
PICO_STDIO_USB_CONNECT_WAIT_TIMEOUT_MS=3000
WANT_HCI_DUMP=1 # This enables btstack debug
#ENABLE_SEGGER_RTT=1
)
But, defining #define WANT_HCI_DUMP 1 only in btstack_config.txt just works.