I watched the webinar given by the developers for the GI engine in Unreal 5.0 early release. The realtime GI requires at this time (in addition to at least a Nvidia RTX 2000 series card) that the walls in your project be separate meshes! The whole thing looked really great but it reminded me of Renderzone Plus, where raytracing does the reflections, AO is handling the nooks and crannies and the final gather handles the big lights. It can do IES and emissives already, but emissives are like the tricks we are already used to (they can't just replace all the lights), except they do propagate in AI. Like always, good diffuse maps win the day. They were also brightening diffuse maps to make them bounce more light.
What is interesting about this is that you can get very sharp 4k (and this method doesn't blur textures at close ranges) at frame rates we who are not gamers drool over. In the time of one rendered animation, you could have the whole house presented with lots of pans and sweeps with all sorts of cool lighting. I don't know if UE has the same sort of simple camera animation as TM, but I suspect this GI engine will come to TM in a year or so.
They showed some good solid archvis results. Certainly makes animation easier. I am finding that all the final compressors sort of wash away all the detail and having the ability to make 4k mp4's right of the screen for all intents and purposes I suspect make for awesome 1080p Youtube results.