I think third party devs will use the lowest common denominator for the consoles. So most likely, most third party games will be limiting to the performance of the XSX SSD assuming the rumoured XSS isn't slower. Ps5 will still have some advantages even then when it comes to loading and etc but I think most third party games won't take full advantage of that SSD in terms of developing around it.
As for PC. I think soon enough, PC gamers that are still using Sata based hard drive or SSD will need to upgrade to Nvme otherwise they are gonna see hitching and stuttering. Similar to if you look at the Fallen Order performance between hard drives on consoles and SSDs on PC. I think (but I could be wrong) there are a good amount of Nvme drives out right now that can probably handle XsX's SSD speeds like the 970 Evo.
Anime: Haruhi Nsfw Anime Thread