The so-called "removable SSDs" in the Apple Mac Studio aren't actual SSDs but just raw storage modules. Apple silicon Macs do not use the standard NVMe protocol but instead use their own implementation via PCIe. This means, it is not possible to simply swap-out or add storage at whim to the Mac Studio without matching the exact capacity and vendor and doing a full DFU restore.
https://www.notebookcheck.net/Mac-Studio-SSD-does-not-work-on-NVMe-top-level-ARM64-SSD-controller-in-M1-Ultra-makes-it-nearly-impossible-to-swap-out-or-add-raw-storage-modules.609363.0.html
Problem solved : shortages of microcontrollers
Problem created : can't use 3th party NVMe drives
Apple : two problems solved XD
Yet another revenue ploy. Typical crApple - pay up or else! Of course, crApple customers deserve it. $$ over form over function always.
That's what comes of buying Crapple.
Does the M1 Ultra (dual M1 Max) use both Max flash controllers at once? I was comparing my Ultra 2TB SSD to someone's Max 2TB SSD config and they were posting 3x 4kQD64 random read numbers. But, I am curious if my "slower" SSD is just not being measured correctly if two controllers are being used.