Literally nobody on YouTube, certainly not Linus, has attempted to upgrade the storage modules with a supported configuration that the machine is shipped from the factory with.
There isn't a single other SSD controller on the market that knows how to work with arbitrary quantities of NAND flash chips because it's an unnecessary engineering challenge, I don't know why anybody thinks it's remotely reasonable to expect Apple's to be different.
He showed you CAN replace the SSD modules but only with identic size ones, but you CAN'T upgrade to bigger ones as that triggers the firmware lock.
Watch the video he posted he tried what you mentioned.