Is there a noun to describe the status of something being "indoor" or "outdoor"?

The best preposition that you could use in this scenario is location. For example, you could say "What is the location of this activity?", or to better put it for conversational language, "Where is this activity going to be located?". If it is understood that you know the literal location of it, then English speakers will probably understand that you mean indoors versus outdoors.

I’m not aware of a noun for this. In practice, I would guess and ask if I’m correct: “Will this dinner be indoors?” Since there are only two options, this works well enough. Words get created to fill a need, and this need isn’t common enough to bother.