Yeah, they’re mostly bits of hardware that turn ttl/serial into a USB device. Then you can use minicom or dterm to connect to the host. Mostly used for embedded development, but also useful for debugging servers that are not connecting to the network without having to lug a keyboard and screen.
After they’re connected, if they speak vt110, your terminal emulator can display everything properly
I don’t get this comment. Gnome is not trying to make a walled garden, and Microsoft has taken every chance they get at making walled gardens (Windows phone, windows 8 arm, various proprietary file formats and protocols), they just haven’t been very successful at it.