EDIT: Added soft- to the title, since it was pissing people off. Maybe Iβm still wrong. Idk, itβs just a meme.
Well, GrapheneOs is a bit easier. GOS uses a WebUSB installer, which does a lot of the work for you.
LineageOS requires things like ADB and Fastboot. In my case, however, it was a Samsung device, so I had to install Windows and then mess around with Odin.
I also ended up soft-bricking the device by trying to sideload the OS before it had finished downloading.