To simplify things and help our users to be more productive, we have archived the current forum and focus our efforts on helping developers on Stack Overflow. You can post new questions on Stack Overflow or join our Discord channel.
My two cents: Cordova is the way to go. That functionality not really related to TouchKit, but instead you can have a TouchKit app use the camera like you describe if you use Cordova as well. Taking pictures with Cordova in a Vaadin app is completely doable (I've seen it in a few projects), but there's no explicit documentation for how to create such a project that I know of.