I think Endgame will be a tiny footnote between Infinity War and the D+ series.
I think Vision will be White and emotionless when Shuri reboots him. Vision will still have his memories, and he will remember being in love with Wanda, but be unable to feel it, causing PTSD and a desire to regain what he has lost.
As shown in Infinity War, Wanda and Vizh were wanting to make a life together, so they will likely do that in the D+ series.
If the leaks are to be believed, Wanda attempts to infuse Vision with life, and an "evil spirit" possesses him. Key Point: Vision, in order to be possessed, would need to have a soul, so he would thus regain his humanity. Chthon doing this via Wanda's attempt to restore Vision would make sense; it's him "helping" Wanda, "blessing" Vision.
The Russos said that Wanda is on a journey away from humanity, Vision toward it.
If the hostile neighbour becomes Grim Reaper, he is Erik Williams, brother of Simon Williams, whom appeared in scenes that were cut from GotG2.
I would think Simon would be the friend to Wanda and Vizh, the person who supports them, and instead of Wanda banging Simon, Chthon tricks Vision into thinking that when no such thing happens.
Erik is against Wanda and Vision, and manipulates the locals into turning against them, and Chthon makes Vision do creepy shit to stir shit up (all this pushes Wanda away from her humanity by making her feel isolated).
Agatha Harkness arrives, and she guides Wanda, and teaches her about her powers, and exposits about the Elder Gods. She injects humour alongside seriousness. She genuinely cares for Wanda and Vision and is determined to thwart Chthon.
Chthon making Erik into Grim Reaper would make Vision, in a sense, his brother.