It feels like there must be multiple completely different implementations of LG OLED TVs. I would not say that my LG has a "main screen" of any kind. When I turn mine on it shows the last input that had been used or, if that thing is off, it shows the bouncy egg and "No Signal". If I press the button on the remote that says RECENTS and has a picture of a house on it, which I guess is the "main screen", it maintains the bouncy egg but shows a ribbon of apps on the bottom. Those are my installed apps: Hulu, Prime, Peacock, YouTube, Netflix, Apple TV, and Disney+ happen to be today's recents. Where is this "main screen" where unbidden appvertisements arise?
Mine has been strictly MRU forever. When I look at this video, it does not resemble the software on my LG OLED TV at all. There must be several platforms or generations.