A lot of yall are talking lore, and how we only see solar shades and the like.
But think about this:
The sector we are in is a absolute backwater; so much so that the only battlegroup the Domain sent to our sector was a disgraced one that was sent with only lightly moddified ships. And even back then such ships were extremely powerful. On top of that they sent out Drones, which even to this day are powerful enough to give the factions a run for their money (Mothership anyone?).
So think about it; the Domain had enough resources to send minor terraforming technology onto several worlds, a battlegroup that used its resources to create an entire faction into itself after the gates shutdown, and several drone / survey / cryosleeper ships into what is considered the ass end of nowhere, galactic scale wise.
What do you think the Domain has in its home worlds or core sectors? They'd probably have the tech to completely terraform a 300% hazard planet into a lush 100% hazard oasis, they just don't have the resources to send such powerful technology to our sector before the Gates collapsed considering we are a slum, galactic wise.
So it wouldn't be a surprise if attacking Remnant fleets allows us to find classified blueprints that Tri Tachyon might have stolen and secretly hidden from the Domain before the Gates shut down, and then hid again within the Remnant fleets when they still thought they could control them in the AI wars.
Or maybe a quest to find them, who knows. It'd make them properly end game and still require massive resources to do.