Deeply sympathetic as I am to the goals of the right-to-repair movement, and deeply frustrated as I am by Apple’s storage prices relative to other high-end SSDs, Miani’s conclusions are based on incorrect assumptions about how modern Mac SSDs work. It’s also likely that these modular SSD slots actually do facilitate easier upgrades and repairs than, say, desoldering NAND chips from a logic board and soldering on higher-capacity NAND chips. There are just caveats you need to be aware of first.
This article explains, in detail, how Apple has chosen to structure its SSDs (the controller is in the M1 system on a chip) and why Apple has chosen to pair chips to individual systems for security reasons.
The fact remains: I suspect that sometime, someday, a trained tech might be able to expand the storage in a Mac Studio. But it’s not as simple as buying two Mac Studios and swapping in a different module.