The megastructures themselves have often been thought of and referred to as crash sites - I don't believe this to be the case at all.
I think I am inclined to agree with you here. The "Flower Ships", (which I think we can assume are Thargoid until proven otherwise) and the Barnacles are closely associated. The Barnacles are organic in nature. They "grow" Meta-Alloys. The structures that have been found dotted about the Pleiades are also (according to the scan data collected) organic. And I'm going to assume (until better evidence presents itself) that the Barnacles are Thargoid tech of some sort.
Therefore, I'm of the opinion (FWIW), that these sites are akin to a ship yard. Think about it... The Thargoids are alien. DBOBE has stressed a few times that they are alien in almost every aspect. Their Biology. Their culture. Their tech. And most likely their societal structure. In fact, everything about them is 'alien' to us.
We humans manufacture our tech. Our stations. Our ships. Our weapons. From gathered resources. Thargoids, I believe,
grow theirs - where the resources are. Which makes each and every one of these sites a potential Thargoid capital ship construction facility. They're
growing their invasion force. That's assuming they're ships. They may be something else entirely, who knows. But whatever they are, I reckon they're being grown.
The disrepair that some are in, being "fixed/repaired" by the Scavengers? Well, we know shadowy human forces are at work. Such as INRA for eg. I wouldn't be surprised if they (INRA or whoever they are) have been well aware of our little green friends for some time, and have attempted to sabotage their plans... however... the Thargoids are evolving, or developing immunity against, the Mycoid Virus. INRA know it and are now bricking it.
Perhaps that's why they haven't attacked us yet after pulling us from Hyperspace or at the Barnacles? Humans almost wiped them out with the Mycoid Virus, maybe they're being cautious. However, once they are all fully immune... it's payback time!
And slowly, and surely, they are drawing their plans against us...
Anyway - just my thoughts. Could be wrong. Probably am.
Nicely put together hypothesis BTW OP o7
