That price is still cheaper than the 1TB XBOXSX proprietary expandable storage. And unlike the Xbox expandable storage the PS5’s can be repurposed for other uses like on your home computer. Also because the NVME can be produced by many different companies, the price will only go down. Only Seagate makes the Xbox storage. I think the only benefit of the more expensive Xbox storage is that it’s an enclosed cartridge so you can easily just swap them out. But in the end, I’d rather go with faster, cheaper and modular like the NVME.
So, if you had done 30 seconds of research, you'd know why the expansion slot isn't able to read random "compatible" ssds. The ps5 uses a proprietary ssd that is not a standard ssd and will never be compatible with them. Third parties are going to have to make drives specifically for the ps5 in order for them to work.