Thanks. Hopefully the SSD is accessible too. I have a ~2010 iMac 27" and I had to pull of the front glass of the monitor and disassemble half the computer to replace the HDD with an SSD. That was a gigantic PITA.
I think the SSDs on all the T2 computers are built-in to the mobo — the T2 is the disk controller — so not even a removable card on the back side like the iMacs models up to now.