We have LPDDR4X in Switch OLED but working at half-rate. They can use same memory in stock clocks and already have 2x of bandwidth without do anything. Or slap LPDDR5 and have fun!
(actually LPDDR5X have about the same power draw as LPDDR4X so it's very unlikely I guess)
Man... Just beware - we was here many times. Nintendo is very focused on software and extracting every last bit of their profitable hardware. They just try to be very effective and profitable.
The good news is that games will mostly look and feel excellent, without bugs, no matter on what hardware.