The PS5 does still need some time to load anything, it’s not magic.

It’s not magic, it’s engineering. Games specifically designed for the PS5 can pretty much load instantly. It’s not just the SSDs raw bandwidth. The SSD controller plays a huge role. It can decompress data as it’s loading from the SSD, effectively acting as a bandwidth multiplier. It also communicates directly with the GPU cache.

Remember that PCs are held back by their modular architecture. To allow for an interchangeable GPU it needs to be on a PCIe card with its own separate VRAM. This all comes at a huge performance penalty. Data needs to be copied over the slow PCIe bus to the VRAM before it can be accessed by the GPU. On a PS5 with its unified memory architecture everything is immediately usable once it hits the system RAM. This is a massive advantage when streaming assets.

The big difference is latency. Not how much data it can load per second, but the time between starting a load and the data actually being available. Sony spent a lot of effort in getting this as short as possible throwing a lot of purpose-designed hardware at it. Something you can’t do in a PC because it’s a general purpose machine.

Another huge factor is that every PS5 has the same minimum performance level. The fact that you have a super fast SSD is meaningless because the game has to be designed to work with the crappiest spinning rust HDD that meets the minimum system requirements. So while a PS5 may not be as fast as the best PC that can run the game, it is much faster than the crappiest PC that can run the game, so the developers can optimize for a much faster machine than they can when they have to take into account that crappy low-end PC that has to be able to run it.