I'm not sure about the exact type but no, afaik there's no battery or anything inside. However, sadly, almost anything can and will degrade and we don't yet exactly know when that will be.

But honestly, I've got quite a few old modules around me (eg gb gg lynx pce - though not collections per se mind you) and some of these have seen really rough days but all of them still work fine. So it might not be relevant to our lifespan and easier to put out of our mind, but still it could surprisingly happen. Working in IT though being certain to maintain data is not a trivial matter of redundancy and moving.

Anyhow. Switch 2 games afaik are more akin to ssd because it has to be streaming data at a far quicker pace to the ram, like mkw or cyberpunk. So in a technical sense I would say the risen price is generally worth it. Switch 1 modules are more like slow mass storage (eg SD, the slow ones, explicitly not EX SD).

But back to the point, none of these need "charging" in that sense (but still degrade).