This issue is currently being investigated. One person has provided a save, and another said they would when they were able, but more wouldn't hurt, if possible (especially saves where it is more likely to be able to reproduce the crash, or it consistently crashes with certain actions).
For people who also have the Steam version of the game, and linked their account on the Switch, you can email applicable saves (or a Dropbox or Google drive link, etc) to supportdos2@larian.com.
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin 2 Definitive Edition\PlayerProfiles\<ProfileName>\Savegames\Story' folder.
In Windows Explorer you can zip a file or folder by right clicking on it/them and selecting 'Send To | Compressed (zipped) Folder' (and similarly in OSX/Finder).
Otherwise, hopefully the descriptions will help QA in trying to reproduce this problem (it was not encountered while testing the update).
