Currently Online 
So there was an interview with Epic China regarding various things including the demo. Looks like as far as the demo is concerned, SSDs like the 970 Evo will do just fine if this is to be believed:
"UE5 tech demo on a RTX 2080 & 970 EVO Plus notebook is 1440p40
Epic China engineers’ interview, if you know Chinese you can confirm it by yourself.
https://www.bilibili.com/video/BV1kK411W7fK
53:00, he said his notebook could run at 1440p 40fps+, optimization target is 60fps for next-gen.
2:08:00, SSD bandwidth (for the flying part) isn’t as that high as ppl said, not need a stricted spec SSD (decent SSD is ok).
Someone at TGFCer forum said, the engineer just confirmed to him: RTX 2080 GPU notebook but forgot the exact SSD model, maybe 970 EVO Plus. (http://club.tgfcer.com/thread-8307013-7-1.html 94th post)"
https://www.reddit.com/r/XboxSeriesX/comments/gkskus/ue5_tech_demo_on_a_rtx_2080_970_evo_plus_notebook/
PC Specs: CPU: 7800X3D || GPU: Strix 4090 || RAM: 32GB DDR5 6000 || Main SSD: WD 2TB SN850
