I have the i7 version. The internal ssd is very specific and expensive. Both are M.2 PCIe Gen4*4 OPAL 2242 and I bought the second ssd (1tb) for 220 euro which was a black friday offer with 20% discount. You (almost) can not find other brands with this type of memory.
M1 Macbooks are great but one reason to migrate is the apple silicone being an arm-based chipset. There is more support of software for x64 systems. So it depends on the user and the use case.
