There's also a massive mansion estate near North Oaks you can't enter.
I already mentioned that in this thread and here, it's Westbrook Casino and Club
2. Westbrook Casino and Club
Back in July 2020, official Cyberpunk Twitter shared this concept art and we already found this building is in the game. There is closed tunnel from North Oak to this complex and you can see it on the map. I guess we can expect something similar to The Diamond Casino from GTA V. Exterior looks like it's not just wasted asset, we can see nice textures, parasols, chairs or hot tubs. So I really believe we'll see it in the future. (video, screenshot, visible tunnel).