If you cannot get Go installed on your device either because a binary distribution is missing or there are not enough resources (ram, disk space) to directly compile it from source, but your target operating system and CPU architecture are supported, you can still do a cross-compilation from a host that has a working Go installation on it! There are some things you have to take care of, I thought it was worth sharing them.
Go compiles itself after version 1.4, probabily you need a different approach if you target a previous version.
From this point on, I'll call host the device where you have Go available, target the one where you would like it to be (in my case a raspberry Pi 2 running FreeBSD).
On the host
First we need to get the source from somewhere (here I'm following the official guide)
$ git clone https://go.googlesource.com/go goroot