Alright this was a lot easier than I expected. Thanks Valve!
After digging through the full 332 update zip I found that Valve left their developer init scripts in /etc/init.d/startup. Not sure if they did this intentionally or not but I like it. So first and foremost I was wrong about the Android AOSP thing, it looks like its just a custom linux and the android stuff I was seeing earlier was just from them using the android signing utility for their updates. Basically they use signapk on their zip files which leaves some android stuff in META-INF. So sorry about the false alarm there.
As for enabling ssh on your Steam Link its very easy. All you need to do is get a pendrive and make this file in these folders: /steamlink/config/system/enable_ssh.txt (Note: the file must have some data in it, if enable_ssh.txt is empty it will not work)
Then reboot the Steam Link with the pendrive inserted, after its done connecting to the network you can ssh into the Steam Link as root with the password `steamlink123`
If you want to dig into it some more look in the /etc/init.d/startup/S01config, in there you can see that you can overwrite any system files or flash a older/custom firmware with a usb pendrive.