HELLDIVERS 2 Tech Blog #2 - Opt-in install size reduction beta (from 154Gb to 23Gb)
(store.steampowered.com)
Yeah, PS5 games are made with the assumption that they'll have access to a 5GB/s drive. It makes sense that they might actually benefit from that. I saw a test of Ratchet and Clank running on a HDD and the main difference was the portals that mask the load times were comically long.
And it's true the difference in price isn't that great any more. Personally I've got an older SATA in my PC and a NVME. I try to install to the faster drive where I can, but since my PC actually has a worse CPU than my Legion Go S, I'm not likely to see a lot of benefit from it. I suppose you've got a better chance of picking up a used SATA drive on the cheap if you really need to save money.