Going back to what the repairer is trying to do, I did wonder how long it will take before people crack it, if possible and third party sellers produce RAM/storage chips to be soldered onto closed systems assuming that stuff like OpenCore could get past any firmware/EFI limitations. Apple's move to SoCs has probably killed that one off, though.
Reportedly, a Chinese engineer has managed to upgrade the M1's SSD and RAM but unsurprisingly it was an arduous task and vulnerable to retaliatory measures by Apple, similar to the efforts mentioned here to discourage and prevent user-repairs on newer iPhones.
As for the repairer, here's an update on their saga.
No spoilers from me. I'll be interested in your comments once you've seen it.