A:Answer The latest Macbook Pros and Macbook Airs have dedicated storage on the motherboard and cannot be changed out. You have what you buy upfront. Perhaps you could mount the SanDisk M.2 NVMe in a external case and plug into one of the two ports? It has been recommended to buy enough storage memory on the new MacBooks to hold the operating system and what ever programing you may EVER need or choose to load and store data like photos, music, excel files etc. on an external drive since the onboard memory from Apple is priced oh so dear. Depends how much the $$$'s mean to you.
Older MacBooks i could not answer for, though if the existing drive is an M.2 NVMe I suspect so, but i do no have access to one to check that out. If you already have one with a PCIe SSD however, other than to increase amount of storage if it is smaller, you will not see any real world difference for most task other than a few seconds faster on the reboot perhaps.
