Galaxy Book 3 Pro 360 Motherboard M.2

[TBurns66]

I am seriously considering purchasing the new Galaxy Book 3 Pro 360. But I want more than 1TB of storage.  And I need to keep the uSD card slot available for frequently swapping in and out different cards.

I understand there is a 5G cellular option available in some countries. I am not seeking that, but want to know if the 5G modem (not installed in the US) is soldered to the motherboard, or installed into a "B-Key" M.2 slot?  Typically those internal M.2 cell modems are 30x42mm or 30x52mm.  If that smaller M.2 socket is open, I would be okay with my additional (and physically shorter) SSD having only the 2 lanes of PCIe that would be accessible on that socket.

Alternatively, is the main M.2 socket for 22x80mm SSDs only for single-sided SSDs, or is there enough room (height available) to install a 4TB SSD that has components on both sides of it?

[TBurns66]

Well, I made the leap and purchased the Book3 Pro 360. 

I was able to replace the stock 1TB SSD (a Western Digital PC SN740) with a Western Digital Black SN850X 4TB.
Please note that the WD specification for the SN850X states that it is 0.09 in (2.286mm) thick, just as the stock SN740.  That is not the case. The new 4TB drive is thicker, at nearly 3.1mm thick.  I The extra thickness comes from added components on the bottom of the drive. It fits into the SSD connector, but the other end doesn't lie completely parallel to the main board.  The extra thickness of the new drive did not impact the fit of the bottom cover of the computer.  I've been using it for a couple of weeks and find no issues with it.
As for an additional M.2 slot for a 5G modem, I did not see one when I opened the case. It may be on the other side of the motherboard, but I didn't remove the board to look and see.