I think it’s more of a theme than a sub-plot but the Death troopers are Cyborgs that is 100%

Saw Gerrera is half machine and has iron Lungs.

Benthic / Edrio (two tubes) again he is heavily modified Vader chest box to boot.

Moroff has a Metal plate over his mouth again cybernetic modification.

There is a guy without a head as the tank rolls in Jedha

There is a woman with a hardrive stuck in her head.

I am not making it up.

Notice the hardcore Partisans all have stuff over their mouths. That is from Geonosis battle with the insectocide probably.