Hi this is Thijs!

I see there are some questions directed at me. Some are maybe better to look at together, some I can answer here!

How to do this code in the World script instead of the Portal script?
> Let's look at this one together!

Can portals refer to/lead to HTML pages? (I would love to link some rooms to bitsy pages if possible)
> Yes, definitely! Through the OS object, you get access to all kinds of operating system functionality. 
  See also: https://docs.godotengine.org/en/stable/classes/class_os.html
  To open an HTML page, for example the wiki, you could use:
  OS.shell_open("https://pzwiki.wdka.nl/mediadesign/Main_Page")
  Connect this to your portal, and a new window should open in your default browser! (probably in the background)
  One question to think about: now that the player doesn't teleport, how should this interaction be resolved in-game?

If the game is uploaded as an html page, is it better to have the menu as javascript button on top of the game (canvas item) or to have an in-game menu? Would the in-game menu access the in-game mechanism better? (Such as room change)
> Without knowing the specifics, I would be inclined for an in-game menu. Some reasons:
  * Allows for more easy testing outside of the web export
  * Keeping it all in-game is a step to future-proofing it a little:
      * You don't know how JS / host site / the export will change
      * You don't know where you might want to deploy this project in the future.
  * I expect the data flow is easier
  That said, I'm sure there are also benefits to use a JS wrapper. We can talk about your purposes more to figure this out!