Valve chose the components of the Steam Deck pretty darn carefully. I don’t expect any upgrade path, except what they have done with the OLED, because it would destroy the parity they sought. Part of the Steam Deck platform is giving the developers a set series of specs to shoot for, for portable performance. This advantage is part of how the Deck has competed with its more powerful rivals, alongside the sheer amount of software-level support Valve has offered.
I’m no expert on… well anything… but supposing this isn’t some ROG ALLY ad, why would you buy a second Steam Deck after learning Valve doesn’t support them in your country? That is a lot of money, even for the 64GB model.