I am trying to port the BLE Peripheral UART sample to work on the nrf52840 dongle. It's not in the list of supported board but I don't see why it shouldn't work (at least, the BLE advertising part). I created a new app from the sample and created a build configuration for the nrf52840dongle. I then build the code which succeeds without error. Now, I can't use Visual Studio Code to flash the dongle so I followed the steps here: https://academy.nordicsemi.com/flash-instructions-for-nrf52840-dongle/
I tried with both "merged.hex" and "zephyr.hex" but in both cases, when I use "nrf Connect for Mobile" to scan BLE devices, the dongle doesn't show up. I also tried the same procedure but with the GUI programmer but same error. All that happens after the flash succeeds, is that both leds light up (blue and green). I should mention that I successfully flashed a nrf52840dk which works as expected (the BLE device shows up when scanning with Nrf Connect for Mobile).
What am I doing wrong?
Some logs of what I tried: