Unable to upload code to the Pixl.js running 2.18, disconnects while sending

Ahh, neat - I bet if you added these lines:

     'DEFINES += -DNRF_SDH_BLE_GATT_MAX_MTU_SIZE=131', # 23+x*27 rule as per https://devzone.nordicsemi.com/f/nordic-­q-a/44825/ios-mtu-size-why-only-185-byte­s
     'LDFLAGS += -Xlinker --defsym=LD_APP_RAM_BASE=0x2ec0', # set RAM base to match MTU

You'll find it breaks - similarly if you removed those from the Pixl's python file and built yourself I bet it'd work great.