It wouldn't surprise me if Andor never knew what the hell he was making and as such had no idea it was linked to the Death Star.
That's my take. It's more tragic that way and adds further weight to his death scene on Scarif at the hands of the very weapon he unkowningly helped to build.
A weapon he also helped delay, since the prison break would likely put at least a noticeable work stoppage for that part.
I mean let's get real: given the sheer scale of that project, nothing Cassian did on Narkina 5 helped or hindered the progress of 'Stardust' in any significant way. Even the prison break probably only caused the delay of a few thousand units being delivered in the few weeks it'd take the Empire to set up a new facility (or reset the existing one; this time with better security.) And what's a few thousand units when they could be churning through hundreds of thousands of those components a week. Plus of course the real delays were down to Galen's sabotage. For all we know, that's the 8th time they've done a total tear-down and rebuild of the superlaser focusing assembly trying to track down the problem, and will end up doing it again half a dozen more times before Jedah. I don't see the tragic angle either. It was a willing sacrifice. Ironic maybe, but more so that one of those most directly responsible for the station's ultimate downfall was one of the many many prisoners used to build it, than that it happened to kill him along the way.
The prison stay was a major part in converting him to the cause. As he was an integral part of securing the destruction of the Death Star, it is a case of epic karma for the Empire.
The Empire is still trying to get the construction of the Death Star a secret. So they have to hide what production of things are for. So, there may not be all that many locations building the connecting parts that were being built at Narkina 5. Though to be fair, the Death Star station is basically finished, they just have the superlaser and its system integration parts to install. Everything else on the station should already be operational. So who knows how many people serve on it that will probably never get leave since the place is still top secret.
Also that after credit sequence could also be a "flash forward" 3-4 years into the future (the components that Andor and Kino were working on eventually made it to the assembly point of the first Death Star).
We see a largely-complete external shell (with, as TedShatner10 noted, no dating information). It may be that that's all there is, I could certainly imagine them completing the shell first, to then give a more suitable working environment for the bulk of the construction. dJE
The Rogue One prequel novel did indicate construction of the actual Death Star station was super easy, barely an inconvenience and was complete a few years after ROTS. It took the Empire the rest of the time to figure the weapon out.
Then construction standards changed from one Death Star to the next. As number 2 seemingly had function prioritized over structural completion. it’s very likely that the Emperor ordered a change in priorities as soon as number 1 successfully tested it’s main weapon.
The only problem with this is that if you build your planet killing space station before your planet killing weapon, you potentially paint yourself in a bit of a corner. What if the only way you can get the weapon to work is by increasing its size by 10% and as a result it no longer fits? Realistically you're better off building the gun and then building the station around it once you know how big the gun is and what it's energy requirements are gonna be?
In 13 BBY we had the pre-titles sequence of Rogue One wherein Krennic comes to retrieve Galen because he needs him to work on the weapon. By that point the shell of the station may well be considerably beyond what we saw at the end of ROTS. Within eight more years it could easily be 90% complete.
Just poking in the chat here to say that this is one of the best seasons of TV i've ever watched. Very tightly integrated and very character driven. I absolutely love how they managed to have a primary cast of characters, secondary and tertiary cast - some people who have had little more than a name and 5 minutes of screen time - still brought something to the story. And everyone brought something to the story, including the 2 stiffs on Morlana who started the whole thing. The other SWTV showrunners should pause and take a lesson from what Tony Gilroy was able to accomplish.
Well, the Death Star in ROTS has a wee little dish compared to the final version (and, oddly, also to the plans seen in AOTC) so maybe that did happen, just early on.