I see that after compiling I get to choose between sketch.ino.hex and sketch.ino.with_bootloader.hex
Is it possible to update the bootloader OTA by using this hex file instead? Which is the best bootloader available now, because my nodes are now on 1.3pre (from topic start).

Is using a genuine HLK-PM01 safe when directly connected to mains? I see here that they used extra components for safety.