Well, sort of. The only real block you can add right now is external storage, the rest are just "ideas" that they'd like to make happen.
Reminds me of the expansions for old eighties Macintosh models with a 9" display, which worked in a similar fashion. Each block had the same size feet, and then grooves on the top in which the feet of whatever was above fit - same size as the Mac, of course, to make it all work.
The whole grail is external GPU expansion. All the other things - storage,UPS, audio - are easily achieved over USB, and USB is quite tolerant of fancy connectors and daisy chaining. Everyone and their grandmother have tried their hand at some sort of upgradeable GPUs for laptops, and so far failed - I don't see why Acer would succeed.