LPDDR5

All Apple Silicon M1 / M2 computers.

The Only time you could upgraded the RAM would be at the time of Purchase and If the user chooses to have a Custom Configuration

Example: Stock configuration comes with 8 GB RAM but user choose at time of placing the Order to increase the RAM to say 16 GB RAM

There after - Too Late as RAM is Soldered to the LogicBoard

EDITED

the mX cpu lines has the memory build into the system on a chip it can't be upgraded without replacing the whole cpu, not a upgrade I believe apple offers