There is also a source code release if you want to dive into that level of detail: https://github.com/EpicGames/UnrealEngine/releases/tag/5.0.0...
I don't think the released details are that surprising to those working on realtime computer graphics, but the engineering details and tradeoffs are certainly interesting. Epic has the budget and business case to allocate a team, including some of the best graphics engineers in the industry, to do R&D for over a year to make this a reality.
The major difference seems to be they've done the work end to end to handle all the occlusion corner cases as well as a sophisticated mesh and texture streaming implementation that targets modern SSDs.
And most of us doesn't use fast SSDs like in PS5 and it works really well. Also these engineers said, it even works just fine with slowers HDDs too. Because, they don't stream meshes for each camera movements. But it's a continuos setup.