The basis of it is *mostly* lore friendly, though it does go a bit off here and there.
Sotha Sil did build a bunch of cyborgs, who presumably kept functioning and going on adventures after he 'died'.
The actual clockwork city is so big that it basically fills the entire core of Nirn, but it is slowly returning to it's wild, untamed state since Sil left.
Divayth Fyr is assumed to have survived into the 4th era, as did Yagrum Bagarn who recovered from corprus to a unspecified degree.
The Thalmor almost certainly have plenty of pointy eared Aribert Heim and Josef Mengele types running around.
Memory and the stuff about Sotha Sil surviving by uploading himself into the city/planet is in that nebulous category of 'considered to be part of the lore until a game directly contradicts it'
And as far as guns are concerned, even the Redguards had black powder cannons 300 hundred years, the only reason there aren't firearms (both magic and mundane) everywhere by the 4th era is because the devs desperately want to hold on the medieval theme, no matter how little sense it makes in the setting.
Seriously, fuck the Dawnguard DLC for acting like xbows were some amazing new technology, in a setting that had god damn moon bases and spaceships in very nearly living memory.