My personal and never-asked-for wish is fairly small - Backlit buttons. Id like the ABXY and Steam/start/select/Menu button to have a faint glow to them with a toggle on/off/dim in the menu. Maybe even the analog stick could glow where the current sticks are white.

For the gen pop I think the low hanging fruit of upgrades people would actually be interested in would be:

• Battery upgrade, or some kind of switch-like efficiency upgrade that makes the battery much more effective
• Some kind of screen improvement, be it smaller bezels or an OLED option or even both.
• A general change in the ergonomics based on user feedback. I personally like the deck as is but Ive been surprised by stuff I didnt notice before

Beyond that its going to be niche improvements that some people may find interesting and others not so much:

• SD and USB slot changes (additions, change in position)
• Various internal changes with the hard drive or upgradability options

It is a bit head scratching, but I have no idea what goes into world wide logistics. And now in the states they are even offering refurbished Decks, so they certainly appear to have enough product at this point to open things up. But maybe they dont have enough to open them up without creating another multi-month long backlog they dont want?? Who knows