Also yes, the original kickstand made me wonder if anyone at Nintendo had actually tried to use it more than once. It's by far my least favorite part of the Switch.
The GB Color is also twice as fast and has more than double the RAM. (Although one can argue if it's an upgrade or a real "separate" console)
The New 3ds has been mentioned, which is more than 8 times faster and has double the ram.
The only handheld generation where Nintendo didn't do this was the GBA, so it's very common.
Though, I would still argue a 4K upgrade is a little far fetched. Nintendo hardware has always been less powerful than that of its 'competitors', who only recently started pushing 4K. (whether or not Nintendo actually competes with Sony and Microsoft is a whole other discussion :P).
Since we're talking things that affect portability/battery life in general: The GBA SP, aside from being their first foldable handheld, was the first with an internal light and a built-in rechargeable battery (instead of taking AA or AAA batteries).