MartinR wrote:
No M-series Mac can be hardware upgraded after purchase. Memory & SSD are embedded in the logic board. There is no hard drive or even an SSD that could be replaced.
There are two special cases which "prove the rule" of soldered-in SSDs.
The Mac Studios and the Mac Pro minitowers have socketed flash modules, instead of soldered-in flash chips. In Mac Studios, the flash modules require such extensive disassembly to reach that they are more "repairable" than "upgradable." You could replace them if the alternative was tossing the whole machine; but otherwise, they might as well be soldered in.
Apple sells flash modules for the M2 Ultra Mac Pros. $1000 for 2 TB, $1600 for 4 TB, or $2800 for 8 TB.
Apple 4TB SSD Upgrade Kit for [M2 Ultra] Mac Pro
These require special installation – including resetting the Mac (with the aid of another Mac), reinstalling macOS,
and restoring your data from backups. You can't "just" drop them into the M2 Ultra Mac Pro because every Apple Silicon Mac encrypts and decrypts most of the contents of the internal SSD in real-time, using keys held within the M-series processor. A new module must be initialized using the correct keys.