As far as I know this wasn't covered in the various matrix related addn sourcebooks, and I'm gathering its more from a 'kind of like how we don't want to really give rules on how PCs could bypass the fake SIN/ID system and do it themselves' I'm figuring its a 'we don't really want to put rules towards this' for things like 'can I build my own fairlight excal quality deck and open source/program it myself?"
I also get something of the sense of "once you get a Fairlight Excal, if ever, you could jailbreak it and fiddle with its stuff so its not ratting out on you or doing automatic updates without your consent/etc' but also no one in the setting has done a 'I've cloned the OS of a Fairlight Excal that you guys can use on your homebrew tinkered decks you made'
In terms of the way the rules set it up, there's no option to buy your own individual components and 'build your own desktop/cyberdeck' without it being anything better than a rating 1, even if you were Fastjack or something. There was also an aside of commlink descriptions that went "you can't have a rating 3 commlink and make it look like a rating 6 one' and 'you can't have a rating 6 one and make it look like a rating 3 one' I mean sure, Form Function you could make the casing look different but it would 'be obvious' you're running a high tier device if you had one, instead of making it seem worse than it is. Which....sounds like it bypasses the whole 'edit icon' kind of thing. You can make your gun look like a potato with RFID if you want, but not make a commlink DR 6 look worse than it is?
Anyway, back to cyberdecks and stuff. It made me wonder, since Fairlights are actually pretty rare out in the world, especially if you do something like "Fairlight Paladin, yep, there are less than 20 in the WHOLE WORLD" you start thinking, "Why would you ever buy one? Wouldn't that make you immediately noticeable to GOD?" Hey guys look, there's some guy using one of the 17 Paladins in the world over here, wonder what's going on? kind of thing.
Going back to my original jailbreak thought, I figure much like modern smartphones and stuff, or computer OS/etc, they get updates. Probably some data sharing info back to the manufacturer. Now, any runner would immediately try their best to disable those functions and either do like I think...Glitch?...does by checking all updates line by line before letting it touch his stuff.
I think about Windows 10 and such, you can sorta do 'free no license windows 10' with some restrictions and such, but it also kind of feels like in setting that OS is way specific to hardware and there isn't really a true no license version unless you hack it somehow. Higher end deck manufacturers want to maintain that exclusivity, so I don't know/don't believe there would be a "Linux for FL Excalibur" would there?