Other World Computing sells MacBook (and other Mac) SSD upgrades in two flavors: drive only, or as a kit.
If you have a supported model, the easiest way to upgrade is to purchase a kit. Given time though, there may be potential for MacBooks and other hard-to-upgrade products to have an approved process for futureproofing by swapping internal components, so while this is certainly a non-recommended enthusiast project, it does add weight to potential life-extending methods that could be implemented for devices. If your model isn’t supported, then, unfortunately, you can’t upgrade the SSD. It's far better to pay upfront for a MacBook Air or MacBook Pro with larger storage if you're worried about the specs than it is to try and Frankenstein an upgrade to the machine yourself.
The discovery itself that this can be achieved is of course commendable, but the practical applications are fairly nonexistent. You'd also need to be very proficient in soldering – given that one mistake will leave you with a very expensive paperweight – and have all the suitable equipment to hand, which doesn't make this a cheap upgrade for the average Joe. The DRAM and NAND memory (a type of nonvolatile flash) are extremely hard to come by for everyday consumers, usually being purchased by large manufacturing companies. We can't stress enough that this is a bad idea to try yourself, not only because of the high risk of it not working (and the obvious voided warranty), but the work required also simply isn't worth the payoff. Enter product line: Enter model: Find my upgrades. Check supported configurations Mac Pro supports up to 12 DIMMs installed in configurations of 4, 6, 8, 10, or 12 DIMMs, as shown in the images below. RAM availability varies by country and region. If you need to order replacement memory, contact Apple. See also See if your Mac shares space across APFS volumes in System Information See used and available storage space on your Mac. You can purchase memory upgrade kits by visiting an Apple Store or Apple Authorized Reseller.
For instructions on how to upgrade or add memory, click Memory Upgrade Instructions.
See more Perfectly impractical in every way Choose Apple menu > About This Mac, then click Memory.