I would like to open a specific scene in a new tab.
In order to open something in a new tab, it must be a separate web page. So the way I’d suggest to do this is that to open the scene you use a Go to URL action that is set to Open in new window (generally a tab for most users nowadays!).
As for the URL field, there is a method (requiring a little code) that lets you use an anchor/hash on a URL that can jump to the particular scene. So you’d use the .html page with this # tag. See the post here for how to do that part:
It means that there is no simple solution for this? Writing code does not scar me, but it’s not very handy in this context…
To setup URLs for your scenes, you add a snippet of code to run ‘On Scene Load’ from the post @jonathan posted. Then, to link to a scene, you put in the full URL to your Hype document (ending with #SceneName) and check ‘Open in New Window’. Two minutes, tops.