Upgradable, yes. Easy, not necessarily. The T480s requires you to open/separate the whole bottom of the laptop to access those parts. The T430 allowed you to replace the RAM and HDD by removing a couple of screws and unhooking the latch. Definitely easier to do for most people.That seems reasonably upgradeable to me.
I will admit the T480s is easier to upgrade than say a 16" MacBook Pro.