Didn't it say somewhere that sollux being prototyped into Erisolsprite drew out the half dead part of him and made him fully blind so that was why he had two eyepatches? My question is, since we see that the pre retcon timeline still exists in the dream bubbles, is Sollux fully alive still post retcon?

Yep. There’s actually TWO Solluxes in the Bubbles it seems, and potentially two Aradias as well. A Fully Alive, Fully Blind Sollux, and a Sollux that’s Half Dead and Half Blind. We see Fully Blind Sollux in Collide, and Half-Dead Sollux on Terezi: Remem8er.