Thanks. What say you? Doubt?
From what he has described for the smaller one, it's a Space Grey aluminum slab on a black aluminum pedestal. That sounds like an Apple design to me.
The "monolith" is a clamshell where the top and bottom come off to allow access. The CPU is on a card, so it might not be designed to be user-replaceable, but third parties (OWC?) might be able to engineer them. There are 8 user-accessible RAM DIMM slots which means either AMD Epyc or Intel Xeon-SP CPUs. The GPU is electrically compatible with PCI-E, but is a custom board like the processor card and is designed to be replaceable. And then there are four "drive sleds" that can hold M.2 SSDs. All of this sounds reasonable for Apple - it's modular and the most-likely to be modified components (RAM and storage) are user-accessible and the CPU and GPU are designed to be upgradeable by Apple and possibly end-users.