I’m betting on what we’re seeing there not being the real world, but a simulation running in Dolores’ own robot CPU, or a virtual sandbox for her AI to survive/be stored in. So ‘Christina’ is an avatar for Dolores within her own virtual reality. Dolores as we know her is currently a repressed memory hidden away in the back of Christina’s mind.

I think the place Christina lives in is a park. When she was on her way to work she was passed by a group of visitors talking excitedly about how wild this place is. She writes stories for NPCs. The guy that's stalking her is an NPC that isn't happy about the story she's written for him. That would be the dark story her boss referenced earlier when she was at work. When she wakes every morning, it's exactly the same as Delores waking in S1. There was the choice between black and white shoes. At the end when the guy is attacked in the street and then disappears, that's because the clean-up squad have paused everything, removed the fight, and then unpaused everything, making it look like a disappearance.All points to it being a "park" of sorts.

We haven't met CharlotteHale/Delores this season yet (All complicated by there having been about half a dozen Delori last season), but she replaced the MiB with a robit, at the end of S3, so I'm expecting her to be pulling the strings on the data deal at the Hoover Dam (perhaps she's now the senator that was referenced?), and I'm guessing she wants to bring her people back from the sublime and reintroduce them into the real world, hence her buying up all the surrounding land, maybe to give them somewhere to live in the real world. Who fucking knows? How this all ties in with Maeve and and Caleb being hunted down is anyone's guess though.