oh and generating custom NixOS iso's is absolutely incredible, this small snippet of Nix is all you need to creat fully configured system installers (with things like enabling serial, opening ssh) https://github.com/asconix/nixos-setup-minimal-installation-cd/blob/master/iso.nix

@irl linking the voltage lines together would probably be a bad idea too, or what it seems like they're talking about, just directly connecting wires. This is a usb > serial > serial > usb bridge with just a shared ground so totally safe

@irl no those grounds are directly connected to the usb plug ground, but I think that's a good thing (not that it should matter much in most cases where they both plug into the same wall earth anyways)