Don't know if anyone else have mentioned this, because search box is not that reliable, but I can't turn in the quest item. The waypoint points to this chair in the Aldecaldos camp, and I can't interact with it.

(There's supposed to be a screenshot in this post, but I hope people know what I'm talking about.)

Is this where you are getting some implant to save somebody's son? Try talking to Bob, the one who gave you the quest, and give the implant to him.

Been trying to talk to him. No chat prompt appears.

In that case, my only suggestion is to use a mod, CyberEngineTweaks, from NexusMods and use the dev console.
https://www.reddit.com/r/cyberpunkgame/comments/kfwr1b/restartingresetting_quest_objectives_on_pc/

But I haven't tried debugging a quest like this myself before.

Did you by any chance patch the game in the middle of this quest?
Because that's the sort of thing that can break quest triggers like this.