In theory, I suppose that you could upgrade them.
https://www.tomshardware.com/news/an-enthusiast-added-an-external-gpu-to-the-steam-deck
An Enthusiast Added an External GPU to the Steam Deck
Why? Why not!
Then put a 4TB USB-C NVMe drive on the thing.
Then put a swap partition on that.
Then a 4k monitor on the HDMI or DisplayPort interface.
I mean, it's not gonna be ideal for portability, but...