Just bought the Samsung T5 500GB SSD and ran some speed tests against the PS4 slim HDD. Not scientific by any means but got some some interesting results. See comment below. Btw
Samsung T5 2TB External SSD Only Showing as 43.92MB on PS4? : r/PS4
UNBOXING. Speedup game loading with Samsung Portable SSD T5 on PS4 - GTA, Call of Duty, Fortnite - YouTube
Samsung 500GB T7 2.5" USB C 3.2 Portable External Solid State Drive SSD 1050MB/s 8806090312397 | eBay
PSA: If you are playing on current-gen consoles, installing the game on an external SSD (instead of the internal HDD) can massively improve texture loading and pop-in! : r/cyberpunkgame