I'm guessing not (it's already wrapped in the box) and I imagine it can't be accessed by software alone. Like, blown fuses.
The storage is expandable externally, and the RAM is actually quite usable even on heavy loads.
I have tried a variety of methods of expanding the storage. I bought an M1 system with this very thought.
None of the USB storage devices I tried worked well. MacOS drops every device I tried periodically. Sometimes it would go as long as a week, but I'd have to yank it and plug it back in for it to continue to work. Very unreliable for a permanent storage augmentation.
NFS doesn't work, MacOS issues. Samba has been the most reliable network storage drive method, but it tends to be slow on my middling servers - and I really tried to optimize it.
If you really want to do this, I suggest trying the thunderbolt route.
the storage is not expandable actually. 256 is pathetic unless you only have cloud based workflows (which is what apple wants obvious for that reoccuring revenue).
disclaimer: Sienna owner.