Hey, Switch digitizers stared popping up on aliexpress a while ago! E.g. this search. Just make sure not to use "nintendo switch" as search term, because it always returns zero results.

You can find replacement shells for both, Switch and JoyCons and replacement for USB ports on AliExpress. The seller also has lots of 3DS parts, and are expanding their Switch catalogue, so maybe they will the ones you look for in future. UPDATE: Digitizers starts showing up eg. here.

People in this reddit thread claim that, similarly to 3DS, Switch's memory modules are not swappable. Apparently memory modules are locked behind device's unique key.

I ordered replacement shell for switch from AliExpress and didn't have time to install it yet, but judging by the looks of it, it is identical to the original. I can update you when I manage to install it.